HOME PAGE * KS3 SCIENCES * GCSE BIOLOGY CHEMISTRY PHYSICS * ADVANCED LEVEL CHEMISTRY

KS3 SCIENCE KS3 CHEMISTRY QUIZZES

KS3 CHEMISTRY QUIZZES

Doc B's revising KS3 SCIENCE

Doc Brown's Chemistry

I appreciate SAT levels have gone, but I hope these KS3 chemistry Quizzes will still be of some use. Although I've already produced some combined KS3 chemistry quizzes, I welcome suggestions from teachers so I may produce useful compilation KS3 chemistry quizzes suitable for any school doing KS3 chemistry and any KS3 chemistry scheme of work now that the KS3 chemistry levels and KS3 chemistry SAT exams have gone.

Copying of the KS3 chemistry quizzes is NOT permitted but you can printout the KS3 chemistry questions to use in class or for homework.

The first part of the page is the most important - the links to the KS3 Chemistry multiple choice quizzes.

The rest of the page is lots of guidance for doc b to help design the most useful KS3 Chemistry quizzes


For after KS3 SCIENCE ...

GCSE 9-1 Chemistry Notes * GCSE 9-1 Biology Notes * GCSE 9-1 Physics Notes



KS3 Chemistry and Earth Science Multiple Choice Questions

The KS3 Chemistry Questions are selected at random from big databases.

PLEASE NOTE: (1) <= back on the link bar returns you to the previous web page.

(2) Don't use the usual refresh button on the upper browser to repeat the quiz, use the    REPEAT QUIZ - fresh Q's    on the quiz link bar.

(3) A small proportion questions are deliberately very challenging and more like GCSE level, but only the odd one! and most cover the full range of ability of KS3 science students.


Multiple choice quizzes for KS3 CHEMISTRY & Earth Science  (other quizzes are listed further down the page)

Currently being re-edited and extended to cover the 2018+ National Curriculum for KS3 Science Chemistry

I've left the old work scheme references 7E-H, 8E-H and 9E-H for my own reference.

By each quiz link is a summary of the quiz content.

  1. KS3 Chemistry Quiz - 7E Acids and alkalis QUIZ 7E "Acids and alkalis" Questions on common acids/alkalis - pH scale, indicators, neutralisation reaction, uses etc.

  2. KS3 Chemistry Quiz - 7F Simple chemical reactions QUIZ 7F "Simple chemical reactions" Questions on the idea of chemical reaction (reactants => products), new materials, acid + metal/carbonate reaction, burning/combustion reaction.

  3. KS3 Chemistry Quiz - 7G Particle model of solids, liquids and gases QUIZ 7G "Particle model of solids, liquids and gases" Questions on the explaining the properties of gases, liquids and solids using particle models and state changes. updated

  4. KS3 Chemistry Quiz - 7H Solutions QUIZ 7H "Mixtures" Questions on particle models of mixtures, rock salt purification,  purification, solute, solvent, solution, solubility, methods of separating mixtures - filtration, evaporation, distillation, chromatography. updated

  5. KS3 Chemistry Quiz - 8E Atoms and elements QUIZ 8E "Atoms, elements, compounds, simple formulae, simple reactions" Questions on elements - different types of atoms making up materials, types of element - metals/non-metals, compounds and molecules, simple chemical reactions. updated

  6. KS3 Chemistry Quiz - 8F Compounds and mixtures QUIZ 8F "Elements compounds and mixtures" Questions on comparing the properties and differences between elements, compounds and mixtures, melting and boiling points, idea of pure/impure. updated

  7. KS3 Chemistry Quiz - 8G Rocks and weathering QUIZ 8G "Rocks and weathering" Questions on properties of rocks, chemical and physical weathering, transport of sediment, formation of sedimentary rocks.

  8. KS3 Chemistry Quiz - 8H The Rock Cycle QUIZ 8H "The Rock Cycle" Questions on the formation of, and differences between, types of rock - sedimentary, igneous and metamorphic rocks, the Rock Cycle.

  9. KS3 Chemistry Quiz - 9E Reactions of metals and metal compounds QUIZ 9E "Reactions of metals and metal compounds" Questions on uses and properties of metals, reaction of metals, metal oxides or metal carbonates with acids, salt preparations.

  10. KS3 Chemistry Quiz - 9F Patterns of reactivity QUIZ 9F "Patterns of reactivity" Questions on reactions of metals with air (oxygen), water and acids, reactivity series of metals, displacement reactions, uses of the reactivity series in predicting the outcome of a reaction and uses of displacement reactions, uses and sources of metals.

  11. KS3 Chemistry Quiz - 9G Environmental chemistry QUIZ 9G "Environmental chemistry" Questions on types of soil, the formation and environmental effects of acid rain, monitoring pollution, global warming.

  12. KS3 Chemistry Quiz - 9H Using chemistry QUIZ 9H "Using chemistry" Questions on burning fuels as energy resources, chemistry of combustion reactions, new materials are made by chemical reactions, useful chemicals like medicines, making a fuel cell.



QCA TOPIC in KS3 CHEMISTRY word-fill worksheets and crossword puzzles


KS3 science-CHEMISTRY 7E Acids and alkalis

KS3 Chemistry guidance notes - 7E Acids and alkalis Summary of the QCA criteria the KS3 Chemistry Quiz - 7E Acids and alkalis quizzes are based on.

KS3 Chemistry 7E Acids and alkalis word-fill worksheets 7Ewf1-4 four handy linked word-fill worksheets * 7Ewf2 * 7Ewf3 * 7Ewf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle - 7E Acids and alkalis BIG OR the smaller EASIER KS3 Chemistry crossword puzzle - 7E Acids and alkalis SMALL version

matching pair quiz KS3 Chemistry matching pairs Quiz - 7E Acids and alkalis on pH and KS3 Chemistry matching pairs Quiz - Hazard warning symbols on hazard symbols

The 7E crossword and word-fill KS3 Chemistry 7E Acids and alkalis answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 7F Simple chemical reactions

KS3 Chemistry guidance notes - 7F Simple chemical reactions Summary of the QCA criteria the KS3 Chemistry Quiz - 7F Simple chemical reactions quizzes are based on.

KS3 Chemistry word-fill worksheets - 7F Simple chemical reactions 7Fwf1-4 four handy linked word-fill worksheets * 7Fwf2 * 7Fwf3 * 7Fwf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry 7F Simple chemical reactions crossword puzzle BIG OR the smaller EASIER KS3 Chemistry 7F Simple chemical reactions crossword puzzle SMALL version

The 7F crossword and word-fill KS3 Chemistry 7F Simple chemical reactions answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 7G Particle model of solids, liquids and gases

KS3 Chemistry guidance notes - 7G Particle model of solids, liquids and gases Summary of the QCA criteria the KS3 Chemistry Quiz - 7G Particle model of solids, liquids and gases quizzes are based on.

KS3 Chemistry word-fill worksheets - 7G Particle model of solids, liquids and gases 7Gwf1-4 four handy linked word-fill worksheets * 7Gwf2 * 7Gwf3 * 7Gwf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle - 7G Particle model of solids, liquids and gases BIG OR the smaller EASIER KS3 Chemistry crossword puzzle - 7G Particle model of solids, liquids and gases SMALL version

3 linked matching pair exercises on the states of matter KS3 Chemistry matching pairs Quiz - 7G Particle model of solids, liquids and gases and * States2mp and States3mp

The 7G crossword and word-fill KS3 Chemistry 7G Particle model of solids, liquids and gases answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 7H Solutions (solubility, salt purification and chromatography etc.)

KS3 Chemistry guidance notes - 7H Solutions (solubility, salt purification and chromatography etc.) Summary of the QCA criteria the KS3 Chemistry Quiz - 7H Solutions quizzes are based on.

KS3 Chemistry word-fill worksheets - 7H Solutions (solubility, salt purification and chromatography etc.) 7Hwf1-4 four handy linked word-fill worksheets * 7Hwf2 * 7Hwf3 * 7Hwf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 7H Solutions (solubility, salt purification and chromatography etc.) OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 7H Solutions (solubility, salt purification and chromatography etc.) version

KS3 Chemistry matching pairs Quiz - 7H Solutions (solubility, salt purification and chromatography etc.) matching pair exercise on keywords

The 7H crossword and word-fill KS3 Chemistry 7H Solutions (solubility, salt purification and chromatography etc.) answers to word-fill worksheets and crossword puzzles answers



KS3 science-CHEMISTRY 8E Atoms and elements

KS3 Chemistry guidance notes - 8E Atoms and elements Summary of the QCA criteria the KS3 Chemistry Quiz - 8E Atoms and elements quizzes are based on.

KS3 Chemistry word-fill worksheets - 8E Atoms and elements 8Ewf1-4 four handy linked word-fill worksheets * 8Ewf2 * 8Ewf3 * 8Ewf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 8E Atoms and elements OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 8E Atoms and elements version

KS3 Chemistry element name/symbol Quiz type in element symbol/name quiz

The 8E crossword and word-fill KS3 Chemistry 8E Atoms and elements answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 8F Compounds and mixtures

KS3 Chemistry guidance notes - 8F Compounds and mixtures Summary of the QCA criteria the KS3 Chemistry Quiz - 8F Compounds and mixtures quizzes are based on.

KS3 Chemistry word-fill worksheets - 8F Compounds and mixtures 8Fwf1-5 five handy linked word-fill worksheets * 8Fwf2 * 8Fwf3 * 8Fwf4 * 8Fwf5 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 8F Compounds and mixtures OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 8F Compounds and mixtures version

KS3 Chemistry matching pairs Quiz - 8F Compounds and mixtures matching pair picture quiz on elements, compounds and mixtures

The 8F crossword and word-fill KS3 Chemistry 8F Compounds and mixtures answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 8G Rocks and weathering

KS3 Chemistry guidance notes - 8G Rocks and weathering Summary of the QCA criteria the KS3 Chemistry Quiz - 8G Rocks and weathering quizzes are based on.

KS3 Chemistry word-fill worksheets - 8G Rocks and weathering 8Gwf1-4 four handy linked word-fill worksheets * 8Gwf2 * 8Gwf3 * 8Gwf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 8G Rocks and weathering OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 8G Rocks and weathering version

The 8G crossword and word-fill KS3 Chemistry 8G Rocks and weathering answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 8H The Rock Cycle

KS3 Chemistry guidance notes - 8H The Rock Cycle Summary of the QCA criteria the KS3 Chemistry Quiz - 8H The Rock Cycle quizzes are based on.

KS3 Chemistry word-fill worksheets - 8H The Rock Cycle 8Hwf1-4 four handy linked word-fill worksheets * 8Hwf2 * 8Hwf3 * 8Hwf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 8H The Rock Cycle OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 8H The Rock Cycle version

KS3 Chemistry matching pairs Quiz - 8H The Rock Cycle matching pair exercise on rock types

The 8H crossword and word-fill KS3 Chemistry 8H The Rock Cycle answers to word-fill worksheets and crossword puzzles answers



KS3 science-CHEMISTRY 9E Reactions of metals and metal compounds

KS3 Chemistry guidance notes - 9E Reactions of metals and metal compounds Summary of the QCA criteria the KS3 Chemistry Quiz - 9E Reactions of metals and metal compounds quizzes are based on.

KS3 Chemistry word-fill worksheets - 9E Reactions of metals and metal compounds 9Ewf1-5 five handy linked word-fill worksheets * 9Ewf2 * 9Ewf3 * 9Ewf4 * 9Ewf5 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 9E Reactions of metals and metal compounds OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 9E Reactions of metals and metal compounds version

The 9E crossword and word-fill KS3 Chemistry 9E Reactions of metals and metal compounds answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 9F Patterns of reactivity

KS3 Chemistry guidance notes - 9F Patterns of reactivity Summary of the QCA criteria the KS3 Chemistry Quiz - 9F Patterns of reactivity quizzes are based on.

KS3 Chemistry word-fill worksheets - 9F Patterns of reactivity 9Fwf1-6 six handy linked word-fill worksheets * 9Fwf2 * 9Fwf3 * 9Fwf4 * 9Fwf5 * 9Fwf6 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 9F Patterns of reactivity OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 9F Patterns of reactivity answers

The 9F crossword and word-fill KS3 Chemistry 9F Patterns of reactivity answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 9G Environmental chemistry

KS3 Chemistry guidance notes - 9G Environmental chemistry Summary of the QCA criteria the KS3 Chemistry Quiz - 9G Environmental chemistry quizzes are based on.

KS3 Chemistry word-fill worksheets - 9G Environmental chemistry 9Gwf1-3 handy linked word-fill worksheets * 9Gwf2 * 9Gwf3 *

The BIG hard on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 9G Environmental chemistry OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 9G Environmental chemistry version

The 9G crossword and word-fill KS3 Chemistry 9G Environmental chemistry answers to word-fill worksheets and crossword puzzles answers


KS3 science-CHEMISTRY 9H Using chemistry

KS3 Chemistry guidance notes - 9H Using chemistry Summary of the QCA criteria the KS3 Chemistry Quiz - 9H Using chemistry quizzes are based on.

KS3 Chemistry word-fill worksheets - 9H Using chemistry 9Hwf1-4 four handy linked word-fill worksheets * 9Hwf2 * 9Hwf3 * 9Hwf4 *

The BIG on-line crossword puzzle KS3 Chemistry crossword puzzle BIG - 9H Using chemistry OR the smaller EASIER KS3 Chemistry crossword puzzle SMALL - 9H Using chemistry version

The 9H crossword and word-fill KS3 Chemistry 9H Using chemistry answers to word-fill worksheets and crossword puzzles answers



SEE ALSO the KS3 Science Quiz compilations

20 Question multiple choice QUIZ on  ORGANISMS, BEHAVIOUR and HEALTH

20 Question multiple choice QUIZ on CHEMICAL and MATERIAL BEHAVIOUR

20 Question multiple choice QUIZ on ENERGY, ELECTRICITY and FORCES

20 Question multiple choice QUIZ on THE ENVIRONMENT, EARTH and UNIVERSE


TOP OF PAGE


National Curriculum KS3 Science CHEMISTRY specification

Subject content – KS3 Chemistry Pupils should be taught about:

KS3 chemistry: The particulate nature of matter     (National Curriculum KS3 science-chemistry)

the properties of the different states of matter (solid, liquid and gas) in terms of the particle model, including gas pressure,

changes of state in terms of the particle model.

KS3 chemistry: Atoms, elements and compounds     (National Curriculum KS3 science-chemistry)

a simple (Dalton) atomic model,

differences between atoms, elements and compounds,

chemical symbols and formulae for elements and compounds,

conservation of mass changes of state and chemical reactions.

KS3 chemistry: Pure and impure substances     (National Curriculum KS3 science-chemistry)

the concept of a pure substance,

mixtures, including dissolving,

diffusion in terms of the particle model,

simple techniques for separating mixtures: filtration, evaporation, distillation and chromatography

the identification of pure substances.

KS3 chemistry: Chemical reactions     (National Curriculum KS3 science-chemistry)

chemical reactions as the rearrangement of atoms,

representing chemical reactions using formulae and using equations,

combustion, thermal decomposition, oxidation and displacement reactions,

defining acids and alkalis in terms of neutralisation reactions,

the pH scale for measuring acidity/alkalinity; and indicators,

reactions of acids with metals to produce a salt plus hydrogen,

reactions of acids with alkalis to produce a salt plus water,

what catalysts do.

KS3 chemistry: Energetics     (National Curriculum KS3 science-chemistry)

energy changes on changes of state (qualitative),

exothermic and endothermic chemical reactions (qualitative).

KS3 chemistry: The Periodic Table     (National Curriculum KS3 science-chemistry)

the varying physical and chemical properties of different elements,

the principles underpinning the Mendeleev Periodic Table,

the Periodic Table: periods and groups; metals and non-metals,

how patterns in reactions can be predicted with reference to the Periodic Table,

the properties of metals and non-metals,

the chemical properties of metal and non-metal oxides with respect to acidity.

KS3 chemistry: Materials     (National Curriculum KS3 science-chemistry)

the order of metals and carbon in the reactivity series,

the use of carbon in obtaining metals from metal oxides,

properties of ceramics, polymers and composites (qualitative).

KS3 chemistry: Earth and atmosphere     (National Curriculum KS3 science-chemistry)

the composition of the Earth,

the structure of the Earth,

the rock cycle and the formation of igneous, sedimentary and metamorphic rocks,

Earth as a source of limited resources and the efficacy of recycling,

the carbon cycle,

the composition of the atmosphere,

the production of carbon dioxide by human activity and the impact on climate.



AQA KS3 Science Chemistry Specification

AQA KS3 chemistry 3.5 Matter

3.5.1 Particle model

Relate the features of the particle model to the properties of materials in different states

AQA KS3 chemistry Know

Properties of solids, liquids and gases can be described in terms of particles in motion but with differences in the arrangement and movement of these same particles: closely spaced and vibrating (solid), in random motion but in contact (liquid), or in random motion and widely spaced (gas).

Observations where substances change temperature or state can be described in terms of particles gaining or losing energy.

Fact A substance is a solid below its melting point, a liquid above it, and a gas above its boiling point.

Keywords

Particle: A very tiny object such as an atom or molecule, too small to be seen with a microscope.

Particle model: A way to think about how substances behave in terms of small, moving particles.

Diffusion: The process by which particles in liquids or gases spread out through random movement from a region where there are many particles to one where there are fewer.

Gas pressure: Caused by collisions of particles with the walls of a container.

Density: How much matter there is in a particular volume, or how close the particles are.

Evaporate: Change from liquid to gas at the surface of a liquid, at any temperature.

Boil: Change from liquid to a gas of all the liquid when the temperature reaches boiling point.

Condense: Change of state from gas to liquid when the temperature drops to the boiling point.

Melt: Change from solid to liquid when the temperature rises to the melting point.

Freeze: Change from liquid to a solid when the temperature drops to the melting point.

Sublime: Change from a solid directly into a gas.

AQA KS3 chemistry Apply

Explain unfamiliar observations about gas pressure in terms of particles.

Explain the properties of solids, liquids and gases based on the arrangement and movement of their particles.

Explain changes in states in terms of changes to the energy of particles.

Draw before and after diagrams of particles to explain observations about changes of state, gas pressure and diffusion.

AQA KS3 chemistry Extend

Argue for how to classify substances which behave unusually as solids, liquids or gases.

Evaluate observations that provide evidence for the existence of particles.

Make predictions about what will happen during unfamiliar physical processes, in terms of particles and their energy.
 

3.5.2 Separating mixtures Devise ways to separate mixtures, based on their properties

AQA KS3 chemistry Know

A pure substance consists of only one type of element or compound and has a fixed melting and boiling point.

Mixtures may be separated due to differences in their physical properties.

The method chosen to separate a mixture depends on which physical properties of the individual substances are different.

Skill Use techniques to separate mixtures.

Fact Air, fruit juice, sea water and milk are mixtures. Liquids have different boiling points.

Keywords

Solvent: A substance, normally a liquid, that dissolves another substance.

Solute: A substance that can dissolve in a liquid.

Dissolve: When a solute mixes completely with a solvent.

Solution: Mixture formed when a solvent dissolves a solute.

Soluble (insoluble): Property of a substance that will (will not) dissolve in a liquid.

Solubility: Maximum mass of solute that dissolves in a certain volume of solvent.

Pure substance: Single type of material with nothing mixed in.

Mixture: Two or more pure substances mixed together, whose properties are different to the individual substances.

Filtration: Separating substances using a filter to produce a filtrate (solution) and residue.

Distillation: Separating substances by boiling and condensing liquids.

Evaporation: A way to separate a solid dissolved in a liquid by the liquid turning into a gas.

Chromatography: Used to separate different coloured substances.

 AQA KS3 chemistry Apply

Explain how substances dissolve using the particle model.

Use the solubility curve of a solute to explain observations about solutions.

Use evidence from chromatography to identify unknown substances in mixtures.

Choose the most suitable technique to separate out a mixture of substances

AQA KS3 chemistry Extend

Analyse and interpret solubility curves.

Suggest a combination of methods to separate a complex mixture and justify the choices.

Evaluate the evidence for identifying a unknown substance using separating techniques.
 



3.5.3 Periodic table Sort elements using chemical data and relate this to their position in the periodic table

AQA KS3 chemistry Know

The elements in a group all react in a similar way and sometimes show a pattern in reactivity.

As you go down a group and across a period the elements show patterns in physical properties.

Facts

Metals are generally found on the left side of the table, non-metals on the right.

Group 1 contains reactive metals called alkali metals.

Group 7 contains non-metals called halogens.

Group 0 contains unreactive gases called noble gases.

Keywords

Periodic table: Shows all the elements arranged in rows and columns.

Physical properties: Features of a substance that can be observed without changing the substance itself.

Chemical properties: Features of the way a substance reacts with other substances.

Groups: Columns of the periodic table.

Periods: Rows of the periodic table.

AQA KS3 chemistry Apply

Use data to describe a trend in physical properties.

Describe the reaction of an unfamiliar Group 1 or 7 element.

Use data showing a pattern in physical properties to estimate a missing value for an element.

Use observations of a pattern in chemical reactions to predict the behaviour of an element in a group.

AQA KS3 chemistry Extend

Predict the position of an element in the periodic table based on information about its physical and chemical properties.

Choose elements for different uses from their position in the periodic table.

Use data about the properties of elements to find similarities, patterns and anomalies.
 

3.5.4 Elements Compare the properties of elements with the properties of a compound formed from them

AQA KS3 chemistry Know

Most substances are not pure elements, but compounds or mixtures containing atoms of different elements.

They have different properties to the elements they contain.

Skills

Use particle diagrams to classify a substance as an element, mixture or compound and as molecules or atoms.

Name simple compounds using rules: change non-metal to –ide; mono, di, tri prefixes; and symbols of hydroxide, nitrate, sulfate and carbonate.

Fact The symbols of hydrogen, oxygen, nitrogen, carbon, hydrogen, iron, zinc, copper, sulfur, aluminium, iodine, bromine, chlorine, sodium, potassium and magnesium.

Keywords

Elements: What all substances are made up of, and which contain only one type of atom.

Atom: The smallest particle of an element that can exist.

Molecules: Two to thousands of atoms joined together.

Most non-metals exist either as small or giant molecules.

Compound: Pure substances made up of two or more elements strongly joined together.

Chemical formula: Shows the elements present in a compound and their relative proportions.

Polymer: A molecule made of thousands of smaller molecules in a repeating pattern.

Plastics are man-made polymers, starch is a natural polymer.
 

AQA KS3 chemistry Apply

Name compounds using their chemical formulae.

Given chemical formulae, name the elements present and their relative proportions.

Represent atoms, molecules and elements, mixtures and compounds using particle diagrams.

Use observations from chemical reactions to decide if an unknown substance is an element or a compound.

AQA KS3 chemistry Extend

Use particle diagrams to predict physical properties of elements and compounds.

Deduce a pattern in the formula of similar compounds and use it to suggest formulae for unfamiliar ones.

Compare and contrast the properties of elements and compounds and give a reason for their differences.

Describe and explain the properties of ceramics and composites.
 



3.6 Reactions

3.6.1 Metals and non-metals Use experimental results to suggest an order of reactivity of various metals

AQA KS3 chemistry Know

Metals and non-metals react with oxygen to form oxides which are either bases or acids.

Metals can be arranged as a reactivity series in order of how readily they react with other substances.

Some metals react with acids to produce salts and hydrogen.

Facts

Iron, nickel and cobalt are magnetic elements.

Mercury is a metal that is liquid at room temperature.

Bromine is a non-metal that is liquid at room temperature.

Keywords

Metals: Shiny, good conductors of electricity and heat, malleable and ductile, and usually solid at room temperature.

Non-metals: Dull, poor conductors of electricity and heat, brittle and usually solid or gaseous at room temperature.

Displacement: Reaction where a more reactive metal takes the place of a less reactive metal in a compound.

Oxidation: Reaction in which a substance combines with oxygen.

Reactivity: The tendency of a substance to undergo a chemical reaction.

AQA KS3 chemistry Apply

Describe an oxidation, displacement, or metal acid reaction with a word equation.

Use particle diagrams to represent oxidation, displacement and metal-acid reactions.

Identify an unknown element from its physical and chemical properties.

Place an unfamiliar metal into the reactivity series based on information about its reactions.

AQA KS3 chemistry Extend

Deduce the physical or chemical changes a metal has undergone from its appearance.

Justify the use of specific metals and non-metals for different applications, using data provided.

Deduce a rule from data about which reactions will occur or not, based on the reactivity series.
 

AQA KS3 chemistry 3.6.2 Acids and alkalis

AQA KS3 chemistry Devise an enquiry to compare how well indigestion remedies work

AQA KS3 chemistry Know

The pH of a solution depends on the strength of the acid: strong acids have lower pH values than weak acids.

Mixing an acid and alkali produces a chemical reaction, neutralisation, forming a chemical called a salt and water.

Facts

Acids have a pH below 7, neutral solutions have a pH of 7, alkalis have a pH above 7.

Acids and alkalis can be corrosive or irritant and require safe handling.

Hydrochloric, sulfuric and nitric acid are strong acids.

Acetic and citric acid are weak acids.

Keywords

pH: Scale of acidity and alkalinity from 0 to 14.

Indicators: Substances used to identify whether unknown solutions are acidic or alkaline.

Base: A substance that neutralises an acid – those that dissolve in water are called alkalis.

Concentration: A measure of the number of particles in a given volume.
 

AQA KS3 chemistry Apply

Identify the best indicator to distinguish between solutions of different pH, using data provided.

Use data and observations to determine the pH of a solution and explain what this shows.

Explain how neutralisation reactions are used in a range of situations.

Describe a method for how to make a neutral solution from an acid and alkali.

AQA KS3 chemistry Extend

Given the names of an acid and an alkali, work out the name of the salt produced when they react.

Deduce the hazards of different alkalis and acids using data about their concentration and pH.

Estimate the pH of an acid based on information from reactions.
 

AQA KS3 chemistry 3.6.3 Chemical energy

AQA KS3 chemistry Investigate a phenomenon that relies on an exothermic or endothermic reaction

AQA KS3 chemistry Know

During a chemical reaction bonds are broken (requiring energy) and new bonds formed (releasing energy).

If the energy released is greater than the energy required, the reaction is exothermic.

If the reverse, it is endothermic.

Keywords

Catalysts: Substances that speed up chemical reactions but are unchanged at the end.

Exothermic reaction: One in which energy is given out, usually as heat or light.

Endothermic reaction: One in which energy is taken in, usually as heat.

Chemical bond: Force that holds atoms together in molecules.

AQA KS3 chemistry Apply

Use experimental observations to distinguish exothermic and endothermic reactions.

Use a diagram of relative energy levels of particles to explain energy changes observed during a change of state.

AQA KS3 chemistry Extend

Predict whether a chemical reaction will be exothermic or endothermic given data on bond strengths.

Use energy data to select a reaction for a chemical hand warmer or cool pack.
 

AQA KS3 chemistry 3.6.4 Types of reaction

AQA KS3 chemistry Investigate changes in mass for chemical and physical processes

AQA KS3 chemistry Know

Combustion is a reaction with oxygen in which energy is transferred to the surroundings as heat and light.

Thermal decomposition is a reaction where a single reactant is broken down into simpler products by heating.

Chemical changes can be described by a model where atoms and molecules in reactants rearrange to make the products and the total number of atoms is conserved.

Skill Write word equations from information about chemical reactions.

Keywords

Fuel: Stores energy in a chemical store which it can release as heat.

Chemical reaction: A change in which a new substance is formed.

Physical change: One that changes the physical properties of a substance, but no new substance is formed.

Reactants: Substances that react together, shown before the arrow in an equation.

Products: Substances formed in a chemical reaction, shown after the reaction arrow in an equation.

Conserved: When the quantity of something does not change after a process takes place.

AQA KS3 chemistry Apply

Explain why a reaction is an example of combustion or thermal decomposition.

Predict the products of the combustion or thermal decomposition of a given reactant and show the reaction as a word equation.

Explain observations about mass in a chemical or physical change. Use particle diagrams to show what happens in a reaction.

AQA KS3 chemistry Extend

Compare the pros and cons of fuels in terms of their products of combustion.

Use known masses of reactants or products to calculate unknown masses of the remaining reactant or product.

Devise a general rule for how a set of compounds reacts with oxygen or thermally decomposes.

Balance a symbol equation.

Use mass of reactant in equation to determine mass of product eg magnesium and oxygen.
 



AQA KS3 chemistry 3.7 Earth

AQA KS3 chemistry 3.7.1 Earth structure

Model the processes that are responsible for rock formation and link these to the rock features

AQA KS3 chemistry Know

Sedimentary, igneous and metamorphic rocks can be inter converted over millions of years through weathering and erosion, heat and pressure, and melting and cooling.

Fact The three rock layers inside Earth are the crust, the mantle and the core.

Keywords

Rock cycle: Sequence of processes where rocks change from one type to another.

Weathering: The wearing down of rock by physical, chemical or biological processes.

Erosion: Movement of rock by water, ice or wind (transportation).

Minerals: Chemicals that rocks are made from.

Sedimentary rocks: Formed from layers of sediment, and which can contain fossils. Examples are limestone, chalk and sandstone.

Igneous rocks: Formed from cooled magma, with minerals arranged in crystals. Examples are granite, basalt and obsidian.

Metamorphic rocks: Formed from existing rocks exposed to heat and pressure over a long time. Examples are marble, slate and schist.

Strata: Layers of sedimentary rock.

AQA KS3 chemistry Apply

Explain why a rock has a particular property based on how it was formed.

Identify the causes of weathering and erosion and describe how they occur.

Construct a labelled diagram to identify the processes of the rock cycle.

AQA KS3 chemistry Extend

Identify circumstances that indicate fast processes of change on Earth and those that indicate slower processes.

Predict planetary conditions from descriptions of rocks on other planets.

Describe similarities and differences between the rock cycle and everyday physical and chemical processes.

Suggest how ceramics might be similar to some types of rock.
 

AQA KS3 chemistry 3.7.2 Universe

Relate observations of changing day length to an appropriate model of the solar system

AQA KS3 chemistry Know

The solar system can be modelled as planets rotating on tilted axes while orbiting the Sun, moons orbiting planets and sunlight spreading out and being reflected.

This explains day and year length, seasons and the visibility of objects from Earth.

Our solar system is a tiny part of a galaxy, one of many billions in the Universe.

Light takes minutes to reach Earth from the Sun, four years from our nearest star and billions of years from other galaxies.

Keywords

Galaxy: Collection of stars held together by gravity. Our galaxy is called the Milky Way.

Light year: The distance light travels in a year (over 9 million, million kilometres).

Stars: Bodies which give out light, and which may have a solar system of planets.

Orbit: Path taken by a satellite, planet or star moving around a larger body.

Earth completes one orbit of the Sun every year.

Exoplanet: Planet that orbits a star outside our solar system.

AQA KS3 chemistry Apply

Describe the appearance of planets or moons from diagrams showing their position in relation to the Earth and Sun.

Explain why places on the Earth experience different daylight hours and amounts of sunlight during the year.

Describe how space exploration and observations of stars are affected by the scale of the universe.

Explain the choice of particular units for measuring distance.
 

AQA KS3 chemistry Extend

Predict patterns in day length, the Sun’s intensity or an object’s shadow at different latitudes.

Make deductions from observation data of planets, stars and galaxies.

Compare explanations from different periods in history about the motion of objects and structure of the Universe.
 

AQA KS3 chemistry 3.7.3 Climate

Investigate the contribution that natural and human chemical processes make to our carbon dioxide emissions

AQA KS3 chemistry Know

Carbon is recycled through natural processes in the atmosphere, ecosystems, oceans and the Earth’s crust (such as photosynthesis and respiration) as well as human activities (burning fuels).

Greenhouse gases reduce the amount of energy lost from the Earth through radiation and therefore the temperature has been rising as the concentration of those gases has risen.

Scientists have evidence that global warming caused by human activity is causing changes in climate.

Facts

Methane and carbon dioxide are greenhouse gases.

Earth’s atmosphere contains around 78 % nitrogen, 21 % oxygen, <1 % carbon dioxide, plus small amounts of other gases.

Keywords

Global warming: The gradual increase in surface temperature of the Earth.

Fossil fuels: Remains of dead organisms that are burned as fuels, releasing carbon dioxide.

Carbon sink: Areas of vegetation, the ocean or the soil, which absorb and store carbon.

Greenhouse effect: When energy from the sun is transferred to the thermal energy store of gases in Earth’s atmosphere.

AQA KS3 chemistry Apply

Use a diagram to show how carbon is recycled in the environment and through living things.

Describe how human activities affect the carbon cycle.

Describe how global warming can impact on climate and local weather patterns.

AQA KS3 chemistry Extend

Evaluate the implications of a proposal to reduce carbon emissions.

Evaluate claims that human activity is causing global warming or climate change.

Compare the relative effects of human-produced and natural global warming.
 

AQA KS3 chemistry 3.7.4 Earth resources

Predict the method used for extracting metal based on its position in the reactivity series

AQA KS3 chemistry Know

There is only a certain quantity of any resource on Earth, so the faster it is extracted, the sooner it will run out. Recycling reduces the need to extract resources.

Most metals are found combined with other elements, as a compound, in ores.

The more reactive a metal, the more difficult it is to separate it from its compound.

Carbon displaces less reactive metals, while electrolysis is needed for more reactive metals.

Keywords

Natural resources: Materials from the Earth which act as raw materials for making a variety of products.

Mineral: Naturally occurring metal or metal compound.

Ore: Naturally occurring rock containing sufficient minerals for extraction.

Extraction: Separation of a metal from a metal compound.

Recycling: Processing a material so that it can be used again.

Electrolysis: Using electricity to split up a compound into its elements.

AQA KS3 chemistry Apply

Explain why recycling of some materials is particularly important.

Describe how Earth’s resources are turned into useful materials or recycled.

Justify the choice of extraction method for a metal, given data about reactivity.

Suggest factors to take into account when deciding whether extraction of a metal is practical.
 

AQA KS3 chemistry Extend

Suggest ways in which changes in behaviour and the use of alternative materials may limit the consumption of natural resources.

Suggest ways in which waste products from industrial processes could be reduced.

Use data to evaluate proposals for recycling materials.
 



OCR Twenty First Century Science knowledge and understanding expected before GCSE Chemistry

Chapter C1 Air and water 

What you will learn about air and water  from KS3 Chemistry before GCSE sciences

From study at Key Stages 1 to 3 you will learn:

• be able to explain the properties of the different states of matter (solid, liquid and gas) in terms of the particle model, including gas pressure

• appreciate the differences between atoms, elements and compounds

• be familiar with the use of chemical symbols and formulae for elements and compounds

• know about conservation of mass, changes of state and chemical reactions

• be able to explain changes of state in terms of the particle model

• know that there are energy changes on changes of state (qualitative)

• know about exothermic and endothermic chemical reactions (qualitative)

• understand the carbon cycle

• know the composition of the Earth’s atmosphere today

• know about the production of carbon dioxide by human activity and its impact on climate.

 

Chapter C2: Chemical patterns

What you will learn about Chemical Patterns  from KS3 Chemistry before GCSE sciences

From study at Key Stages 1 to 3 you will learn :

• know the properties of the different states of matter (solid, liquid and gas) in terms of the particle model, including gas pressure

• know changes of state in terms of the particle model

• be aware of a simple (Dalton) atomic model

• know differences between atoms, elements and compounds

• know chemical symbols and formulae for elements and compounds

• know conservation of mass in changes of state and chemical reactions

• understand chemical reactions as the rearrangement of atoms

• be able to represent chemical reactions using formulae and using equations

• know some displacement reactions

• know what catalysts do

• be aware of the principles underpinning the Mendeleev Periodic Table

• know some ideas about the Periodic Table: periods and groups; metals and non-metals

• know how some patterns in reactions can be predicted with reference to the Periodic Table

• know some properties of metals and non-metals.

 

Chapter C3: Chemicals of the natural environment   

What you will learn about chemicals of the natural environment from KS3 Chemistry before GCSE sciences

From study at Key Stages 1 to 3 you will learn

• know the differences between atoms, elements and compounds

• be familiar with the use of chemical symbols and formulae for elements and compounds

• be familiar with the use of formulae and equations to represent chemical reactions

• understand chemical reactions as the rearrangement of atoms

• know about reactions of acids with metals to produce a salt plus hydrogen

• know some displacement reactions

• know the order of metals and carbon in the reactivity series

• know that carbon is used to obtain metals from metal oxides.

 

C4 Material choices

What you will learn about material choices from KS3 Chemistry before GCSE sciences

From study at Key Stages 1 to 3 you should:

• distinguish between an object and the material from which it is made

• identify and name a variety of everyday materials, including wood, plastic, glass, metal, water, and rock

• describe the simple physical properties of a variety of everyday materials

• compare and group together a variety of everyday materials on the basis of their simple physical properties.

• have observed that some materials change state when they are heated or cooled, and measured the temperature at which this happens in degrees Celsius (°C)

• compare and group together everyday materials on the basis of their properties, including their hardness, solubility, transparency, conductivity (electrical and thermal), and response to magnets

• identify and compare the suitability of a variety of everyday materials, including wood, metal, plastic, glass, brick, rock, paper and cardboard for particular use

• know the differences between atoms, elements and compounds

• recognise chemical symbols and formulae for some elements and compounds

• know about the properties of ceramics, polymers and composites (qualitative)

 

Chapter C5 Chemical analysis

What you will learn about chemical analysis  from KS3 Chemistry before GCSE sciences

From study at Key Stages 1 to 3 you should:

• use knowledge of solids, liquids and gases to decide how mixtures might be separated, including through filtering, sieving and evaporating

• understand the concept of a pure substance and how to identify a pure substance

• know about simple techniques for separating mixtures: filtration, evaporation, distillation and chromatography

• know about the pH scale for measuring acidity/ alkalinity; and indicators.

 

Chapter C6 Making useful chemicals

What you will learn about Making useful Chemicals from KS3 Chemistry before GCSE sciences

From study at Key Stages 1 to 3 you should:

• explain that some changes result in the formation of new materials, and that this kind of change is not usually reversible

• represent chemical reactions using formulae and using equations

• define acids and alkalis in terms of neutralisation reactions

• describe the pH scale for measuring acidity/ alkalinity; and indicators

• recall reactions of acids with metals to produce a salt plus hydrogen and reactions of acids with alkalis to produce a salt plus water

• know what catalysts do.

• know about energy changes on changes of state (qualitative)

• know about exothermic and endothermic chemical reactions (qualitative).

 



TOP OF PAGE

multiple choice quizzes for KS3 chemistry, revision notes for KS3 chemistry courses, practice questions for KS3 chemistry pupils help for ks3 chemistry students, syllabus summaries for ks3 chemistry, online questions for ks3 chemistry pupils, what do I need to know for my ks3 chemistry tests? revision for ks3 chemistry exams ks3 chemistry revision free detailed notes on ks3 chemistry to help revise ks3 chemistry revision notes on ks3 chemistry revision free detailed notes on ks3 chemistry free online website to help revise ks3 chemistry how to succeed in questions on ks3 chemistry a good website for free questions on ks3 chemistry

KS3 BIOLOGY QUIZZES ~US grades 6-8 KS3 CHEMISTRY QUIZZES ~US grades 6-8 KS3 PHYSICS QUIZZES ~US grades 6-8 HOMEPAGE of Doc Brown's Science Website EMAIL Doc Brown's Science Website
GCSE 9-1 BIOLOGY NOTES GCSE 9-1 CHEMISTRY NOTES and QUIZZES GCSE 9-1 PHYSICS NOTES GCSE 9-1 SCIENCES syllabus-specification help links for biology chemistry physics courses IGCSE & O Level SCIENCES syllabus-specification help links for biology chemistry physics courses
Advanced A/AS Level ORGANIC Chemistry Revision Notes US K12 ~grades 11-12 Advanced A/AS Level INORGANIC Chemistry Revision Notes US K12 ~grades 11-12 Advanced A/AS Level PHYSICAL-THEORETICAL Chemistry Revision Notes US K12 ~grades 11-12 Advanced A/AS Level CHEMISTRY syllabus-specificatio HELP LINKS of my site Doc Brown's Travel Pictures
Website content © Dr Phil Brown 2000+. All copyrights reserved on revision notes, images, quizzes, worksheets etc. Copying of website material is NOT permitted. Exam revision summaries & references to science course specifications are unofficial.

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry - KS3 SCIENCE-Chemistry QCA Unit 7E Acids and alkalis


KS3 Chemistry In the unit you should learn how to ...

  • classify acids and alkalis as chemicals with distinct properties and uses.
  • use indicators to classify solutions as acidic, alkaline or neutral.
  • use the pH scale to compare the acidity and alkalinity of different solutions.
  • begin to explore neutralisation i.e. the reaction between an acid and an alkali.
  • interpret observations, making comparisons and seeing simple patterns.
  • investigate fairly the effectiveness of different antacids i.e. compare their ability to neutralise acids 
  • recognise and deal with risks and hazards relating to acids and alkalis.
  • name some common acids and alkalis.
  • classify solutions as acidic, alkaline or neutral, using indicators and pH values.
  • describe what happens to the pH of a solution when it is neutralised
  • describe some everyday uses of acids, alkalis and neutralisation

Its handy if you ...

  • know that soluble solids dissolve and form solutions, substances that don't dissolve are insoluble
  • have had experience of mixing materials and seeing that new materials are formed as a result of a reaction between them
  • understand the difference between a reversible and irreversible change (physical or chemical)

Some important words for you to understand, use and spell correctly

  • names of laboratory acids and alkalis, eg hydrochloric acid, sodium hydroxide
  • names of classes of chemical, eg acid, alkali, salts
  • words with different meanings in scientific and everyday contexts, eg indicator, solution, neutral, react, equation, weakly, strongly
  • words with similar but distinct meanings, eg harmful, corrosive, caustic, sour, irritant
  • words and phrases relating to scientific enquiry, eg hazard, risk, pH range, evaluate, strength of evidence, alkaline, acidic, neutral, indicator, universal indicator, colour change, dilute, ?

What are acids and alkalis like and where do we use them?

  • many household materials are acids and are not hazardous eg lemon juice or vinegar
  • identify some everyday uses of acids, eg fruit juices or vinegar in foods, medicines like aspirin, using acids to clean materials like metal plates, oven cleaners can be strongly alkaline
  • recognise and interpret common hazard signs for harmful, irritant and corrosive substances
  • how to deal with acids or alkalis if they are spilt/splashed on the skin eg dilute/wash with lots of water
  • adding water to an acid or alkali solution dilutes it and makes it less hazardous
  • describe how to work safely with acids and alkalis and what to do if a spill occurs, e.g. wear safety goggles, dilute split acids/alkalis
  • acids are distinguished from alkalis using indicators such as litmus or universal indicator
    • (both turn red in acid (pH <3)  or blue in alkali (pH > 9), but universal has lots of colours to get a more accurate estimate of the pH including green for neutral pH7 and how strongly acid from pH 6 to 1 and how strongly alkaline from 8 to 1 etc.4)
  • common names, eg caustic soda (sodium hydroxide), bicarbonate of soda (sodium hydrogencarbonate), may be used where appropriate.
  • Adding water to concentrated sulphuric acid is hazardous because the reaction is highly exothermic, so concentrated sulphuric acid should be diluted by adding a small amount of the concentrated acid to a lot of water.
  • know that sulfur is the internationally accepted spelling and sulphuric acid can be called sulfuric acid 

How can acids and alkalis be identified and distinguished from each other?

  • how to extract the dyes from plant materials and that acids and alkalis can change the colours of some of these natural dyes and that this can be used to classify them eg from red cabbage, raw beetroot, blackcurrant, litmus,
  • to test and classify solutions as acidic, neutral or alkaline, using indicators
  • compare the results with different dyes and establish that there are two classes of solution and that the dyes can indicate which is which
  • recognise that solutions of dyes which show one 'indicator' colour in acids and another in alkalis are called indicators
  • recall the names of some common laboratory acids eg hydrochloric acid, sulphuric acid, sodium hydroxide, and alkalis e.g. sodium hydroxide, calcium hydroxide

Is there a range of acidity and alkalinity?

  • universal indicator gives a range of colours in acidic and alkaline solutions (typically from pH 0-14)
  • that pH numbers indicate how acidic or alkaline a solution is
  • that neutral solutions are pH 7, acidic solutions are below pH 7 and alkaline solutions are above pH 7
  • the pH of a solution can be got from an appropriate colour chart eg when using universal indicator
  • classify the solution as strongly/weakly, acidic/alkaline, or neutral
  • relate their classification to the use of the acid or alkali and associated hazards
  • At this stage, pH can be used to describe strongly or weakly acidic or alkaline solutions.
  • predict the effect on pH of making an acid more dilute or more concentrated and how this would affect its corrosiveness. When diluted, acids still give a pH <7, but when diluted the pH will rise since the solution would be less strongly acidic.

What happens when an acid is added to an alkali?

  • the uses of acids and alkalis in a range of everyday situations, eg hair and skin care, treatment of stings and bites, treatment of indigestion, food preservation, treatment of soil.
  • how living things use acids, eg ants, nettles, humans in digestion.
  • identify and note key points about the range of pH used and potential harmful effects,
  • that a neutral solution can be obtained by adding an acid to an alkali in the right proportions
  • the changes in pH when a solution of an acid is added drop by drop to a solution of an alkali
  • describe that when an acid is added to an alkali, the pH of the mixture falls as it become neutralised
  • describe that when an alkali is added to an acid, the pH of the mixture increases as it become neutralised
  • explain how to obtain a neutral solution of about pH7 by mixing an acid and an alkali
  • describe with a graph the way pH changes as more alkali is added
  • investigate changes in temperature during neutralisation and be introduced to the idea that a chemical reaction is taking place
    • neutralisation is exothermic, which means heat is given out, so the temperature rises.

Where is neutralisation important?

  • the alkali lime is used to treat soil that is too acid for healthy plant growth
  • acid bee stings can be treated with a weak alkali like bicarbonate of soda or calomine (zinc oxide paste)
    • and alkaline wasp stings can be treated with a weak acid like vinegar
  • too much stomach acid! - common antacid indigestion remedies - how are the remedies are intended to work? what sort of solution would work and be safe to take?
    • antacids are mild alkalis including bicarbonate of soda (alka-selza) and magnesium hydroxide ('milk of magnesia')
  • suggest ways in which one remedy might be more effective than others
  • investigating the effectiveness of antacids:
    • does one tablet of each antacid neutralise the same amount of acid?
    • do the antacids neutralise acid equally quickly?
    • how can you follow the neutralisation? e.g. by adding universal indicator and following the colour change
    • how can you measure how much acid is neutralised by a particular mass of 'antacid' powder?
    • is the reaction is fast or slow to the neutralisation point?

KS3 Chemistry About the unit

In this unit pupils:

  learn about acids and alkalis as classes of chemicals with distinct properties and uses

  use indicators to classify solutions as acidic, alkaline or neutral

  use the pH scale to compare the acidity and alkalinity of different solutions

  begin to explore neutralisation

In scientific enquiry pupils:

  recognise hazards and use information sources to assess risks associated with acids and alkalis

  make and present qualitative observations

  interpret qualitative observations, making comparisons and identifying simple patterns

  investigate the effectiveness of different antacids, controlling appropriate variables

KS3 Chemistry Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on unit 6C ‘More about dissolving’ and unit 6D ‘Reversible and irreversible changes’ in the key stage 2 scheme of work.

This unit introduces pupils to chemicals, reactions and practical techniques which are likely to be new to them, through using a range of acids and alkalis encountered in familiar and laboratory contexts. It lays the foundation for work on reactions of acids in unit 9E ‘Reactions of metals and metal compounds’ and work on carbonate rocks in unit 8G ‘Rocks and weathering’ and unit 8H ‘The rock cycle’.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: obtain and present qualitative results in a way which helps to show patterns; describe how to deal with hazards relating to acids and alkalis; suggest how to investigate a question about antacids, planning and making a fair comparison

some pupils will not have made so much progress and will: obtain and present qualitative results; describe some hazards of acids and alkalis; explain how they made a fair comparison in their investigation into antacids

some pupils will have progressed further and will: explain how their conclusions match the evidence obtained and suggest ways in which the data collected could be improved

in terms of materials and their properties

most pupils will: name some common acids and alkalis and classify solutions as acidic, alkaline or neutral, using indicators and pH values; describe what happens to the pH of a solution when it is neutralised; describe some everyday uses of acids, alkalis and neutralisation

some pupils will not have made so much progress and will: name some common acids and alkalis; state some everyday uses of acids and alkalis and classify solutions using indicators

some pupils will have progressed further and will: explain how a neutral solution can be obtained and relate the pH value of an acid or alkali to its hazards and corrosiveness

KS3 Chemistry Prior learning

It is helpful if pupils:

  know that solids can dissolve and form solutions

  have experience of mixing materials and seeing that new materials are formed as a result of a reaction

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  work with acids and alkalis

  plan their own investigations into antacids

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  names of laboratory acids and alkalis, eg hydrochloric acid, sodium hydroxide

  names of classes of chemical, eg acid, alkali

  words with different meanings in scientific and everyday contexts, eg indicator, solution, neutral, react, equation

  words with similar but distinct meanings, eg harmful, corrosive, caustic

  words and phrases relating to scientific enquiry, eg hazard, risk, pH range, evaluate, strength of evidence

Through the activities pupils could:

  ask questions to gain clarification and further information, eg why, how, what then

  find information, eg using contents, index, glossary, key words, hotlinks

KS3 Chemistry Resources

Resources include:

  household acids and alkalis (not bleaches), together with containers

  Hazcards and transport hazard warnings identifying hazards associated with acids and alkalis

  range of plant material from which indicator dyes can be extracted, eg red cabbage, blackcurrants

  pH sensor linked to a computer

  advertisements for products, eg for skin and hair care, which refer to pH

  indigestion remedies

  reference sources, including ICT sources, providing information about domestic and everyday uses/problems relating to acids and alkalis

KS3 Chemistry Out-of-school learning

Pupils could:

  use the internet to search for information, using key words about uses and hazards of acids and alkalis

  observe hazard signs on transport vehicles and in public places

  KS3 Chemistry: What are acids and alkalis like and where do we use them?

   that many household materials are acids and are not hazardous

   Elicit pupils’ ideas about acids by asking them to work in pairs or small groups to suggest words they would use to describe an acid and examples of where acids are used.

   Show pupils a range of household acids that can be safely handled, eg vinegar, fruit juices, and ask them to explore and describe the appearance and smell of these. If appropriate, pupils could be asked to taste drops of the solutions that are food products. Provide packaging or labels from additional household materials (that do not have hazard warnings) and ask pupils to find the names of acids contained in them.

   Ask pupils to compare what they found with the ideas they had about acids, and to highlight differences.

  identify some acids, eg vinegar, lemon juice

  identify some everyday uses of acids, eg in foods, medicines, cleaning materials 

   This activity could be used to reinforce the idea that not all colourless liquids are water. Pupils are likely to have worked with liquids other than water at key stage 2.

Safety  

eye protection should be used when working with acids and alkalis. Teachers should follow school procedures for dealing with spills and splashes

scrupulous hygiene must be observed in all tasting activities

   to recognise and interpret common hazard signs

   to select key ideas from written material

   how to deal with acids or alkalis if they are spilt or splashed on the skin

   that adding water to an acid or alkali solution dilutes it and makes it less hazardous

   Provide pupils with containers for household and laboratory acids and alkalis with hazard warning labels, student safety sheets, Hazcards and information about hazard symbols and ask them to describe the distinctions between them and why the materials they used in the previous activity did not have hazard labels. Ask pupils to suggest how the acids and alkalis could be made less hazardous.

   Consider hazard warning signs used when acids and alkalis are transported by road.

   Ask pupils to suggest why different acids and alkalis are labelled differently and to suggest safety procedures for working with acids and alkalis. Agree a common set of procedures, which should include use of eye protection.

  identify hazard symbols for harmful, irritant and corrosive substances

  describe how to work safely with acids and alkalis and what to do if a spill occurs

  explain that if water is added to an acid or alkali it dilutes it and the solution becomes less hazardous

   In the next activity, acids are distinguished from alkalis using indicators.

   CLEAPSS produces Hazcards and student safety sheets.

   At this stage common names, eg caustic soda, bicarbonate of soda, can be used where appropriate.

   Adding water to concentrated sulphuric acid is hazardous because the reaction is highly exothermic. Concentrated sulphuric acid should be diluted by adding the acid to water.

   It may be helpful to point out that sulfur is the internationally accepted spelling.

Safety

containers should be sealed or empty

  KS3 Chemistry: How can acids and alkalis be identified and distinguished from each other?

   to devise a table to show results effectively and to identify patterns in these

   that acids and alkalis can change the colours of some dyes and that this can be used to classify them

   the names of some common laboratory acids and alkalis

   to classify solutions as acidic or alkaline, using indicators

   Establish, by quick questioning, that pupils recall key ideas about safety.

   Provide pupils with solutions of dyes extracted from plant material, eg red cabbage, raw beetroot, blackcurrant, litmus, and ask them to explore and record the effect of adding household and laboratory acids and alkalis to the dyes.

   Compare the results with different dyes and establish, by comparing results from the class, that there are two classes of solution and that the dyes can indicate which is which. Introduce the terms ‘indicator’ and ‘alkali’.

   Provide pupils with a range of acidic and alkaline solutions and indicators and ask them to use the indicators to identify and record whether the solutions are acidic or alkaline.

  present their results in a way which helps them identify patterns

  recognise that solutions of dyes which show one colour in acids and another in alkalis are called indicators

  recall the names of some common laboratory acids and alkalis

  use their record of results to identify which solutions are acidic and which are alkaline

   Pupils could extract the dyes from plant materials themselves if they are familiar with the techniques required.

Safety

avoid the use of bleach, drain cleaner or descaler. 0.4 mol dm-3 laboratory acids and alkalis can be used for this activity. None are hazard­ous although some are irritants, and eye protection is needed. In general, alkalis are more hazardous to skin and eyes than acids of a similar concentration

   KS3 Chemistry: Is there a range of acidity and alkalinity?

   that universal indicator gives a range of colours in acidic and alkaline solutions

   that pH numbers indicate how acidic or alkaline a solution is

   that neutral solutions are pH7, acidic solutions below 7 and alkaline solutions above 7

   Demonstrate the use of universal indicator paper or solution to obtain a pH number for a few solutions previously tested. Ask pupils to explore the range of pH of solutions previously tested (including some neutral solutions) and to see if they can relate them to earlier work on hazard labels.

  identify the pH of a given solution from an appropriate colour chart

  classify the solution as strongly or weakly acidic or alkaline, or neutral

  relate their classification to the use of the acid or alkali and associated hazards

   Full-range universal indicator pH0–14 should be used for this activity.

   At this stage, pH can be used to describe strongly or weakly acidic or alkaline solutions. It is not necessary to discuss the difference between weak and strong, and dilute and concentrated, although the appropriate terms should be used.

   Extension: pupils could be asked to predict the effect on pH of making an acid more dilute or more concentrated and how this would affect its corrosiveness.

Safety  

0.4 mol dm-3 solutions can be used for this activity. None are hazardous, although some are irritant and eye protection is needed

    KS3 Chemistry: What happens when an acid is added to an alkali?

   that acids and alkalis are used in a range of everyday situations

   how to find information, eg using contents, index, glossary, key words, hotlinks

   to select and note appropriate information about uses and effects of acids and alkali

   Ask pupils to use a range of reference sources including advertisements to find information about the use of acids and alkalis in a range of everyday situations, eg hair and skin care, treatment of stings and bites, treatment of indigestion, food preservation, treatment of soil. Ask them to find out how living things use acids, eg ants, nettles, humans in digestion. Agree with pupils key words they need to use and remind them how to use an index, glossary or search facility. Ask them to identify and note key points about the range of pH used and potential harmful effects, and to explain these to other pupils either orally or by contributing to an information folder.

  identify uses of acids and alkalis and the benefits and potential hazards of these

  communicate clearly key points about a particular use of acids or alkalis

   Advertisements for skin-care and hair-care products could be used to introduce this activity.

   Most pupils will need to be guided towards suitable sources of information, eg websites such as
www.miamisci.org
. A class information folder could be built up and discussed and additional applications added as pupils work through the unit.

   that when an acid is added to an alkali, it lowers the pH

   that a neutral solution can be obtained by adding an acid to an alkali

   Ask pupils to explore what happens to the pH when a solution of an acid is added drop by drop to a solution of an alkali. Challenge pupils to predict what will happen if more acid is added, or if alkali is added to an acid, and test their predictions using a pH monitor and datalogger.

  describe that when an acid is added to an alkali, the pH of the mixture falls and vice versa

  explain how to obtain a neutral solution

  find information in reference books, on CD-ROMs, or from databases

   ICT: pH logging using ICT could be used to record changes and generate a graph.

   Teachers may wish to emphasise that acidity and alkalinity are measured on a continuous scale.

   Extension: pupils could be asked to describe what computer-generated graphs show about the way pH changes as more alkali is added.

   Extension: pupils could be asked to investigate changes in temperature during neutralisation and be introduced to the idea that a chemical reaction is taking place.

Safety  

0.4 mol dm-3 solutions of acid and alkali can be used. These may be irritant, so eye protection is needed

   KS3 Chemistry: Checking progress

   to summarise key ideas about acids, alkalis and neutralisation

   Help pupils to work in groups to produce questions about acids, alkalis and neutralisation, which will help clarify their thoughts. Pupils ask others to answer or find the answers to their questions. Use all the questions and answers and, together with the pupils, agree a summary of key ideas.

  identify key questions about acids and alkalis

  use correct scientific terminology in answering questions

   Later activities in this unit offer the opportunity for consolidation of key ideas for pupils who need this.

   Extension: pupils could also be asked to explore whether mass is conserved as neutralisation takes place. This idea is covered more fully in unit 9H ‘Using chemistry’.

   KS3 Chemistry: Where is neutralisation important?

   how to frame a question that can be investigated

   how to use preliminary work to help decide what to measure or to observe

   to choose appropriate techniques and equipment

   to compare their investigative method and evidence collected with those of others

   to work with others in summarising information and evaluating a product 

   Remind pupils of earlier work about acid in the stomach. Show pupils a range of packages and leaflets for some common antacid indigestion remedies and ask them to identify how the remedies are intended to work and to suggest what sort of solution would work and be safe to take.

   Ask them to suggest ways in which one remedy might be more effective than others and how they might investigate their suggestions.

   Encourage a range of different investigations, eg Does one tablet of each antacid neutralise the same amount of acid? Do the antacids neutralise acid equally quickly? Ask pupils to write a brief account of their suggestions, results and what they found out, to share with other groups in the class. Encourage pupils to question each other about what they did and what they found out.

   Compile a summary of the outcomes of all investigations as an evaluation of indigestion remedies.

  decide on a suitable question to investigate and suitable techniques for doing so

  summarise what they have found out

  demonstrate understanding of the strength of evidence through the questions they ask

  use the evidence collected to evaluate an indigestion remedy  

   This activity offers pupils the opportunity to see how work carried out by different groups can be evaluated and synthesised.

   It is possible to simulate different antacids by mixing bicarbonate of soda and salt in varying proportions.

   It may be helpful to review words used on commercial products, eg antacid, and compare them with scientific terms, eg alkali, as pupils may be confused by the change in terminology.

   As an alternative, pupils could be asked to investigate differences in the acid content of a range of soft drinks.

Safety

teachers should check pupils’ plans for health and safety before practical work begins

   KS3 Chemistry: Reviewing work

   to relate ideas about acids and alkalis to each other

   Help pupils to bring together their knowledge about acids and alkalis by asking them to produce a concept map using terms encountered, eg acid, alkali, strongly acidic, weakly acidic, weakly alkaline, strongly alkaline, neutral, indicator, universal indicator, colour change, corrosive, sour. Ask pupils to comment on others’ maps and additional connections, explaining those shown.

  identify relationships between key ideas

  explain why connections were made

   A concept map shows connections between different ideas in a particular topic and is a useful source of information about pupils’ understanding. Many pupils will be familiar with making concept maps from their work in primary science. Some pupils will require help, eg a range of terms could be written on a large sheet of paper and pupils asked to draw lines between those they think are linked, and to write a phrase or sentence on the lines explaining why they have linked those terms.

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry - KS3 SCIENCE Unit 7F Simple chemical reactions


KS3 Chemistry In this unit you should learn how to ...

  • see that chemical changes result in new material substances that are different from the ones from which they were made
  • explore some simple chemical reactions of acids in which a gas is made
  • explore burning as a chemical reaction involving a gas, air or oxygen
  • identify hydrogen and carbon dioxide gases as real materials made during some of these reactions
  • begin to use word equations as shorthand descriptions of reactions
  • learn techniques for testing for gases, using laboratory equipment effectively and safely
  • investigate the role of air in the burning of a candle
  • generalise that hydrogen is formed when acids react with metals; carbon dioxide when acids react with carbonates; oxides form when materials burn as they react with oxygen
  • describe tests for carbon dioxide and hydrogen and describe burning as a reaction with oxygen

Its handy to  ...

  • know that there are many gases
  • have explored changes in which new materials are formed and which cannot easily be reversed
  • have used the pH scale as a measure of acidity and alkalinity

Some important words for you to understand, use and spell correctly

  • names of gases, eg hydrogen, oxygen, carbon dioxide, methane
  • names of other elements and compounds, eg carbon, zinc, calcium carbonate
  • words and phrases describing chemical reactions, eg reactant, product, word equation
  • words and phrases relating to scientific enquiry, eg line graph, generalisation, evaluate

What is a chemical reaction?

  • to make and interpret observations of chemical reactions to recognise new substances formed
  • everyday materials which react chemically when they are mixed, eg lemon juice and bicarbonate of soda, baking powder and water, plaster of Paris and water
  • describe typical observed changes, eg it bubbled, it felt warm, changes colour
  • generalise that when bubbles are formed a gas is released and this is a new material

How do acids react with metals?

  • how to carry out a lit splint test for hydrogen
  • that acids can be corrosive and corrode metals like magnesium and zinc easily - bubbling to!
  • generalise that when an acid is added to many metals new substances eg hydrogen are produced and the metal disappears (reacts - dissolves!) or becomes smaller to form another substance
  • relate the disappearance of the metal to the idea of corrosion
  • the terms ‘reactant’ and ‘product’ (what you start with, what you end up with!)
  • what happens when a range of acids is added to a range of metals?  make generalisations from the results eg hydrogen always seems to be formed from the chemical change
  • identify that some metal(s), eg copper, do not react with acids to produce hydrogen

How do acids react with carbonates?

  • what the ‘fizz’ in bottled water is - identify the gas as carbon dioxide and demonstrate how to collect carbon dioxide and test for it using limewater.
  • what happens with samples of carbonates, possibly including ...
    • rocks, eg chalk, building materials, marble
    • or household materials, eg baking powder, carbonate indigestion remedies
  • generalise that when an acid is added to a carbonate, carbon dioxide is made and is evidence of a chemical reaction producing new substances

What new substances are made when materials burn in air or oxygen?

  • burning requires oxygen and new substances, usually oxides, are formed when materials burn in air or oxygen (beware of hazards - intense fast reaction)
  • introduction to the idea of word equations as shorthand for simple combustion reactions eg
    • substance + oxygen (reactants) ==> oxides (products)
  • information about fire prevention and firefighting
  • test the pH of the oxide produced and to demonstrate that the product of burning carbon turns lime water cloudy.

What is produced when fuels burn?

  • that fuels are substances that release energy when they burn
  • that fossil fuels are rich in compounds containing carbon form carbon dioxide on burning
  • that natural gas is called methane, and carbon dioxide and water are produced when it burns, and these substances are also formed when wax, ethanol ('alcohol') and wood burn too
  • is it likely that carbon dioxide and water could be turned back into fuel? NO but plants do it!
  • more word equations: methane + oxygen ==> water + carbon dioxide + heat energy
  • energy is NOT a material

What is needed for things to burn?

  • which part of the air is used up during burning?
  • the effect of putting a large glass container over a lighted candle floating on a trough of water and how do we explain what we see?
  • What was in the large container?; Why did the candle go out?; Why didn’t it go out immediately?; Why did the water rise up the container?; What is made when a wax candle burns?; What happens to this?
  • explain that the candle goes out when oxygen is used and why the water rose up the container

KS3 Chemistry About the unit

In this unit pupils:

  are introduced to the idea that chemical change results in new substances that are different from the ones from which they were made

  explore some simple chemical reactions of acids in which a gas is made

  explore burning as a chemical reaction involving a gas, air or oxygen

  identify hydrogen and carbon dioxide as substances made during some of these reactions

  work with gases to understand that gases are real materials

  begin to use word equations as shorthand descriptions of reactions

In scientific enquiry pupils:

  learn techniques for testing for gases, using laboratory equipment effectively and taking action to control risks

  present observations in ways which enable patterns to be seen

  make generalisations from observations

  suggest and evaluate explanations of observations

  investigate the role of air in the burning of a candle

KS3 Chemistry Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on ideas introduced in unit 5C ‘Gases around us’ and unit 6D ‘Reversible and irreversible changes’ in the key stage 2 scheme of work.

This unit relates closely to unit 7E ‘Acids and alkalis’ and these can be used together as an introductory unit in year 7, in which pupils use equipment and techniques they may not have encountered in key stage 2.

An approach to teaching about energy is included in the Teacher’s guide and in the ‘About the unit’ section of unit 7I ‘Energy resources’.

Unit 9E ‘Reactions of metals and metal compounds’ and unit 9F ‘Patterns of reactivity’ include further work on the reactions of acids and on burning as a chemical change. Unit 9H ‘Using chemistry’ includes work on the conservation of mass in chemical reactions, including burning.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: obtain and present qualitative results, identifying patterns in these; work safely with acids and when burning materials; suggest how to test an idea about burning, obtaining results which can be represented as a line graph

some pupils will not have made so much progress and will: obtain and present qualitative results, describe some hazards of acids and of burning; work safely with acids and when burning materials; test an idea about burning and present results

some pupils will have progressed further and will: evaluate how well ideas about burning match the data collected

in terms of materials and their properties

most pupils will: identify that some new materials are formed during a chemical reaction and generalise that hydrogen is formed when acids react with metals, carbon dioxide when acids react with carbonates, and oxides when materials burn; describe tests for carbon dioxide and hydrogen and describe burning as a reaction with oxygen

some pupils will not have made so much progress and will: identify some products of chemical reactions and state that oxygen or air is needed for burning

some pupils will have progressed further and will: predict that carbon dioxide and water will be made when a hydrocarbon burns and use word equations to represent reactions in which materials burn

KS3 Chemistry Prior learning

It is helpful if pupils:

  know that there are many gases

  have explored changes in which new materials are formed and which cannot easily be reversed

  have used the pH scale as a measure of acidity and alkalinity


KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  work with acids

  observe materials burning in oxygen

  burn liquid fuels

  plan their own investigation into burning a candle

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  names of gases, eg hydrogen, oxygen, carbon dioxide, methane

  names of other elements and compounds, eg carbon, zinc, calcium carbonate

  words and phrases describing chemical reactions, eg reactant, product, word equation

  words and phrases relating to scientific enquiry, eg line graph, generalisation, evaluate

Through the activities pupils could:

  collaborate with others to share information and ideas, and solve problems

  group sentences into coherent paragraphs with subheadings as appropriate

KS3 Chemistry Resources

Resources include:

  corroded metals

  building materials including carbonate rocks, eg chalk, marble

  carbonated water

  computer and software to produce information leaflet

  cards on which are written words, phrases and statements about chemical reactions

KS3 Chemistry Out-of-school learning

Pupils could:

  visit a fire station open day to hear talks and see fire-prevention displays

  consider how burning is used in celebrations, eg candles, bonfires, fireworks

   KS3 Chemistry:  What is a chemical reaction?

   to make and interpret observations

   Provide pairs of pupils with everyday materials which react chemically when they are mixed, eg lemon juice and bicarbonate of soda, baking powder and water, plaster of Paris and water. Ask pupils to mix them and make as many observations as they can. Ask pupils to decide and give their reasons for whether a new material has been made. Explain that in each case a chemical reaction has taken place and that in this unit they will find out more about other chemical reactions and what new substances are made.

  describe changes, eg it bubbled, it felt warm

  generalise that when bubbles are formed a gas is released and this is a new material

   In key stage 2 many pupils will have explored changes in which new materials are made (unit 6D ‘Reversible and irreversible changes’) but are less likely to have classified the changes as chemical reactions.

    KS3 Chemistry:  How do acids react with metals?

   how to carry out a test for hydrogen

   that acids can be corrosive

   that acids react with some metals to produce new substances, including hydrogen

   Remind pupils of earlier descriptions of acids as corrosive and show some examples of corroded metals. Establish through a quick class experiment that when an acid is added to a metal, eg zinc, magnesium, bubbles are made.

   Demonstrate an appropriate method for testing the gas produced and explain that a gas behaving in this way is hydrogen.

  describe and carry out the lighted splint test for hydrogen

  generalise that when an acid is added to many metals, hydrogen is produced and the metal disappears or becomes smaller

  relate the disappearance of the metal to the idea of corrosion

   In key stage 2, pupils are likely to have seen reactions of acids producing a gas (unit 6D ‘Reversible and irreversible changes’) and have encountered common gases (unit 5C ‘Gases around us’). However, they will not have tested or identified gases produced.

   It may be helpful to introduce the terms ‘reactant’ and ‘product’.

Safety  

eye protection should be used. 0.4 mol dm-3 acid is suitable. Acids are not necessarily corrosive and most of those encountered by pupils will not be

   to record relevant observations

   to identify and describe patterns in qualitative data

   to identify results which do not appear to fit the pattern 

   Ask pupils to investigate what happens when a range of acids is added to a range of metals and to record and make generalisations from their results.

   Bring together pupils’ results and establish that in most cases a new material, hydrogen, is made, showing that there was a chemical reaction between the acid and the metal.

  use a table to present observations in a way which enables patterns to be seen

  identify metal(s), eg copper, which do not react with acids to produce hydrogen

  conclude that when hydrogen was made a chemical reaction had taken place

   At this stage, it is sufficient for many pupils to identify that acids react with many metals to produce hydrogen. Some teachers may wish to take this further, either by considering what other products are obtained or by considering patterns in reactivity. This is more fully covered in unit 9F ‘Patterns of reactivity’.

    KS3 Chemistry: How do acids react with carbonates?

   how to carry out a test for carbon dioxide

   to produce new substances, including carbon dioxide

   to identify and describe patterns in qualitative data

   to generalise from their observations

   Ask pupils what the ‘fizz’ in bottled water is. Identify the gas as carbon dioxide and demonstrate how to collect carbon dioxide and test for it using lime water.

   Provide pupils with samples of carbonate, possibly including rocks, eg chalk, building materials, eg marble, household materials, eg baking powder, carbonate indigestion remedies, and ask them to investigate the effect of adding a range of acids to these and to record and make generalisations from their results. Establish that in each case a chemical reaction took place and draw out the idea that chemical reactions are important.

  carry out and describe the lime water test for carbon dioxide

  generalise that when an acid is added to a carbonate, carbon dioxide is made

  use a table to present observations in a way which enables patterns to be seen

  conclude that the production of carbon dioxide is evidence of a chemical reaction

   It may be helpful to emphasise that the colourless gas (carbon dioxide) collected in this activity is a different material and behaves differently from the gas collected in the previous activity.

   The effects of acid rain on carbonate building materials are covered in unit 8G ‘Rocks and weathering’.

Safety

eye protection should be worn when lime water is in use

eye protection should be used.
0.4 mol dm
-3
acid is suitable

    KS3 Chemistry: What new substances are made when materials burn in air or oxygen?

   that burning requires oxygen

   that new substances, usually oxides, are formed when materials burn

   to use appropriate scientific terminology and conventions

   how to carry out combustion reactions safely

   to identify and note key points

   to group sentences into coherent paragraphs with subheadings as appropriate

   Demonstrate burning some elements in air and then in oxygen. Emphasise the hazards of burning materials in oxygen. Use secondary sources to illustrate more hazardous reactions. Show pupils how to burn materials safely in oxygen. Ask pupils to describe what they see and point out to them that in each case the new material is an oxide and that a chemical reaction has taken place.

   Introduce the idea of word equations for simple combustion reactions and ask pupils to sort cards showing reactants and products to produce word equations.

   Ask pupils to use secondary sources to find information about fire prevention and firefighting and to produce information sheets, eg for use in the home, explaining key principles.

  describe, eg through producing word equations, burning as a reaction in which a material reacts with oxygen to produce an oxide

  name the products of some reactions

  explain precautions that need to be taken when burning materials and why more care is needed if materials are burnt in oxygen 

  identify key points about fire safety

  express key points clearly in a structured way 

   In key stage 2, pupils will have considered burning as an irreversible change (unit 6D ‘Reversible and irreversible changes’). However, they are unlikely to have considered it in terms of combination with oxygen.

   Some teachers may wish to test the pH of the oxide produced and to demonstrate that the product of burning carbon turns lime water cloudy.

   At this stage word equations are used as shorthand. Teachers may wish to postpone their introduction for some pupils. Units 8E, 8F, 9E, 9F, 9G and 9H deal more fully with equations.

   This activity could be ICT-based.

Safety  

eye protection should be worn by teachers and pupils, who should be seated 2m away. Employer’s risk assessments on the use of elements such as sulphur, phosphorus and magnesium should be consulted

    KS3 Chemistry: Checking progress

   that new materials are made during chemical reactions

   that the products of a reaction can be deduced from the reactants

   Provide pupils with a series of cards showing words or phrases about the chemical reactions, eg reactant, product, metal, acid, carbonate, oxide, carbon dioxide, hydrogen, oxygen, and ask them to group them into three sets to describe the three types of chemical reaction covered in the unit. Help them to use the words or phrases to make generalisations about the three types of reaction.

  identify a product of each type of reaction

  make generalisations about the products of each type of reaction

 

    KS3 Chemistry: What is produced when fuels burn?

   that fuels are substances that release energy when they burn

   that fossil fuels are rich in compounds containing carbon

   that burning fossil fuels results in the production of carbon dioxide

   that natural gas is called methane, and carbon dioxide and water are produced when it burns

   Elicit pupils’ ideas about fuels by asking them what they understand by the term and what examples they can give of fuels. Explain that fossil fuels are rich in carbon and ask pupils to suggest what might be formed when they burn.

   Demonstrate that carbon dioxide (and water) is produced when methane burns. If possible, extend the demonstration by using other fuels containing hydrogen and carbon, eg wax, ethanol, wood. Discuss with pupils whether it is likely that carbon dioxide and water could be turned back into fuel.

   Help pupils make a summary of information about burning fossil fuels.

  name a range of fuels and explain the meaning of the
term ‘fuel’

  generalise that carbon dioxide
is produced when
carbon-containing fuels burn

  summarise burning of methane in a word equation

   The formation of fossil fuels and burning of fuels to release energy is covered in unit 7I ‘Energy resources’. In this unit teachers may wish to concentrate on identifying the products of burning.

   Pupils often think that energy, like gas, is a material and has mass.

   Environmental effects of burning fossil fuels are covered later in unit 9G ‘Environmental chemistry’.

Safety

employer’s risk assessments on the use of fuels should be followed. Eye protection should be worn. Small quantities of fuels should be used and storage bottles kept well away from where the fuels are burnt

    KS3 Chemistry: What is needed for things to burn?

   that part of the air is used up during burning

   to suggest and evaluate explanations

   to suggest how to test an idea

   to produce a line graph from results and to draw conclusions from these

   to collaborate with others to share information and ideas, and to solve problems

   Show pupils the effect of putting a large glass container over a lighted candle floating on a trough of water and ask questions to help them explain what happens, eg
What was in the large container?

Why did the candle go out?
Why didn’t it go out immediately?
– Why did the water rise up the container?
– What is made when a wax candle burns?
– What happens to this?

   Ask pupils in groups to work out explanations. Help them to evaluate their explanations through questioning and establish that part of the air was used up and that the candle could not continue to burn. Link back to earlier work on comparing burning in air and oxygen.

   Extend by asking pupils to investigate the idea that the candle goes out when part of the air is used up. Help them to turn this into a question that can be tested and to devise a way of getting results from which a graph can be plotted.

  explain that the candle goes out when oxygen is used up

  suggest and evaluate ideas about why the water rose up the container

  generalise that the less oxygen there is the sooner the candle would go out and suggest a way of testing this

  draw a line graph of results; describe what it shows, relating this to the oxygen available for burning

  contribute usefully to group work

   This activity provides an opportunity for pupils to suggest their own ideas and to think critically about these and the ideas of others. Teachers may wish to go into detail with some pupils about factors such as expansion of air on heating and solubility of carbon dioxide, but it is not necessary to do so.

   Extension: pupils could be asked to find out about earlier work on burning and oxygen by scientists, eg Lavoisier, Priestley.

Safety  

use candles that are short and difficult to knock over and ensure they are set in a firm base. Teachers should check pupils’ plans for health and safety before practical work begins

    KS3 Chemistry: Reviewing work

   to identify key points about reactions of acids with metals, acids with carbonates and burning

   to group points together to make a summary

   Provide pupils with a series of statements, or ask them to make their own, about the areas covered in the unit. Ask them to work together to choose the most helpful statements for a summary and to group those chosen into four or five main sections. Ask pupils to explain why they chose or rejected particular statements and agree an overall summary with them.

  identify statements which are helpful to a summary

  combine statements into a summary

  give reasons for choosing or rejecting particular statements

 

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry - KS3 SCIENCE Unit 7G Particle model of solids, liquids and gases


KS3 Chemistry In the unit - you should learn how

  • the particle model can be used to explain differences between solids, liquids and gases.
  • experimental evidence relates to theories and models to explain things.
  • to use the particle model to relate scientific theories and evidence.
  • to evaluate whether evidence does or does not support  explanations of observations
  • to describe and explain observations using the particle model.
  • to classify materials as solid, liquid or gas and explain that some materials are 'difficult' to classify.
  • to describe materials as being made of particles and describe the movement and arrangement of them,
  • to use the particle model to explain phenomena, eg the mixing of liquids, the expansion of a metal bar, 'dancing' dust particles etc.
  • to do labelled drawings to describe the arrangement and movement of particles in solids, liquids and gases.

Its handy if you

  • have experience of identifying (classifying) solids, liquids and gases and describing the properties of each.
  • know that the same material can exist as a solid, liquid and gas.
  • have seen that melting solids and freezing liquids are the opposite of each other.
  • have seen and understand what we mean by dissolving, evaporation and condensation take place.
  • have some ideas how to separate gases, liquids and solids

Some important words for you to understand, use and spell correctly:

  • words with a precise meaning in scientific contexts, eg evidence, theory, model, ?
  • words and phrases relating to the particle model, eg particle, diffusion, gas pressure, vibration, ?
  • words relating to scientific enquiry, eg evidence, data, ?

How can we explain evidence from typical experiments?

  • comparing the masses of identically-sized blocks of two or three different materials such as wood, glass and metal - this tells us eg how dense things are, particles have different mass, closer together, ..?
  • putting one small coloured crystal into a beaker of cold water and one into a beaker of hot water - how fast do the particles spread and why?
  • trying to fit a metal bar into a gauge before and after strong heating - shows expansion - the hotter particles vibrate more and spread out.
  • opening a perfume bottle at arm’s length - particles move to our nose!
  • heating one end of a metal rod that has paperclips attached by petroleum jelly - heat moves as vibration from higher to lower temperatures
  • trying to depress the plungers of three sealed syringes, one containing a solid, one a liquid and one a gas - which is the most easily compressed? - the gas - has the most space between particles.
  • putting weights on the end of a thin wire - stretches and then snaps

How are theories created?

  • you share and discuss ideas and suggest theories based on experimental data (evidence).
  • sometimes new evidence results that doesn't fit in and shows the theory needs to be changed and improved.

What are the differences between solids, liquids and gases?

  • classify materials and justify your choice in terms of the properties of solids, liquids and gases,
  • but that some materials are difficult to classify and can you explain why?
  • imagine what you might see if the materials could be seen using an immensely powerful microscope.
  • describe solids, liquids and gases in a way  that fits the evidence and your scientific knowledge, eg a solid is made of tiny grains all glued together
  • do a summary table to classify materials as solid, liquid or gas and show their similarities and differences.
  • take care if you use, or come across, other 'particle' terms  eg atom, molecule.
  • don't confuse microbes, cells and particles and the differences will need to be made explicit. 

How can the particle model explain the differences between solids, liquids and gases?

  • models can be used to explain things which cannot be observed in a direct way.
  • solids, liquids and gases are made up of tiny particle and the differences can be explained in by the distance between, and the motion of their particles.
  • particle theory can explain some phenomena, eg diffusion of a gas, mixing of liquids, expansion of a metal bar.

How can the particle model explain other phenomena?

  • apply a model to new observations to explain behaviour eg
    • placing coloured crystals on agar gel and observing the diffusion of colour
    • placing distinct layers of water and ink in plastic syringes and observing the mixing of colour over a short period of time
    • observing dust particles in a beam of light
    • explain your observations in terms of particles
  • gas particles are moving around all the time so ...
    • gas pressure is caused by particles hitting the walls of the container
    • gases mix by diffusion, eg by mixing bromine and air, or nitrogen dioxide and air (both visible in gas jars)
  • having seen the collapsing can experiment ...
    • explain their observations using the particle theory
    • identify where there are contradictions in ideas to explain the collapsing
    • describe gas particles as moving all the time and pushing against surfaces
    • explain that the can collapses because there are fewer air particles on the inside hitting 'out' than on the outside hitting 'in'.

KS3 Chemistry About the unit

In this unit pupils:

  learn how the particle model can be used to explain differences between solids, liquids and gases

  explore how experimental evidence relates to theories and models

In scientific enquiry pupils:

  use the particle model to explore the interplay between scientific theories and evidence

  evaluate whether evidence supports or refutes explanations of phenomena

KS3 Chemistry Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on unit 4D ‘Solids, liquids and how they can be separated’, unit 5C ‘Gases around us’, unit 5D ‘Changing state’ and unit 6C ‘More about dissolving’ in the key stage 2 scheme of work.

This unit lays the foundation for subsequent work on particles.

Pupils will have many opportunities in later units to try to explain phenomena in terms of particles, eg dissolving in unit 7H ‘Solutions’, changes of state in unit 8I ‘Heating and cooling’, digestion in unit 8A ‘Food and digestion’, crystal size related to rate of cooling in unit 8H ‘The rock cycle’, the behaviour of gases in unit 9L ‘Pressure and moments’.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: describe and explain observations, using the particle model

some pupils will not have made so much progress and will: describe observations and try to offer explanations for them

some pupils will have progressed further and will: compare explanations of a phenomenon and evaluate whether evidence supports or refutes them

in terms of materials and their properties

most pupils will: classify materials as solid, liquid or gas; explain their classification of some ‘difficult’ materials; describe materials as being made of particles and describe the movement and arrangement of these, and begin to use the particle model to explain phenomena, eg the mixing of liquids, the expansion of a metal bar

some pupils will not have made so much progress and will: classify materials as solid, liquid or gas and recognise that materials are made of particles

some pupils will have progressed further and will: use the particle model to explain a range of phenomena

KS3 Chemistry Prior learning

It is helpful if pupils:

  have experience of identifying solids, liquids and gases and describing the properties of each

  know that the same material can exist as a solid, liquid and gas

  have observed that melting solids and freezing liquids are the opposite of each other

  have observed situations in which evaporation and condensation take place

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  carry out a range of experiments which may be hazardous

  observe gases which are toxic and corrosive

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words with a precise meaning in scientific contexts, eg evidence, theory, model

  words and phrases relating to the particle model, eg particle, diffusion, gas pressure, vibration

  words relating to scientific enquiry, eg evidence, data

KS3 Chemistry Resources

Resources include:

  simulation software, three-dimensional models to illustrate particle arrangement and movement in solids, liquids and gases

  cards/information sheets for a ‘murder mystery’ or other problem-solving game

KS3 Chemistry Out-of-school learning

Pupils could:

  look for stories (not necessarily in a scientific context) in newspapers, magazines and on television and radio where evidence is collected and considered, so that they appreciate the variety of situations in which evidence is important

  look for domestic and everyday contexts where gases, liquids and changes of state feature, in order to broaden their experience of the states of matter

    KS3 Biology: How can we explain evidence from experiments?

   to classify materials as solid, liquid or gas

   to use their existing knowledge and understanding to interpret and explain results

   to work together, listening to and evaluating the contributions of others

   that discussion can help clarify ideas

   Check that pupils are familiar with the terms ‘solid’, ‘liquid’ and ‘gas’ and have some understanding of what these mean. Present them with examples and ask them to allocate each example to the appropriate class.

   Introduce the idea that pupils will work in groups to carry out some quick experiments which will help them explain why solids, liquids and gases behave differently, eg

comparing the masses of identically-sized blocks of two or three different materials such as wood, glass and metal

– putting one small coloured crystal into a beaker of cold water and one into a beaker of hot water

– trying to fit a metal bar into a gauge before and after strong heating

– opening a perfume bottle at arm’s length

– heating one end of a metal rod that has paperclips attached by petroleum jelly

– trying to depress the plungers of three sealed syringes, one containing a solid, one a liquid and one a gas

– adding small weights, one at a time, to a thin wire suspended from a clamp until it snaps

   Ask pupils to discuss with others what they observe and try to explain what has happened.

   If pupils cannot give any explanations to start with, it may be helpful to suggest that they try to imagine they can see what is happening through powerful microscopes.

   Ask groups of pupils to present observations and to describe and explain them, eg through oral, flip-chart or overhead-projector (OHP) presentation. Discuss different ideas with pupils and ask them to compare their own ideas with those of others.

  classify materials as solid, liquid or gas

  offer explanations (which may be incorrect) in which they try to link their existing knowledge to observations, eg

the syringe which contains a solid won’t squash because it’s got no air in it

the metal rod expands because the particles get bigger

  evaluate their own explanations and those given by others

   These activities should be carried out quickly. Their purpose is to encourage pupils to look for and give explanations for their observations. Most pupils will have incorrect ideas at this stage. They should be encouraged to evaluate them and compare them with those of others. They will be introduced to accepted explanations later in the unit.

   It may be helpful to have key phrases prepared for pupils to use.

   This work links to unit 7A(ii) ‘Understanding materials (resistant materials)’ in the design and technology scheme of work.

Safety

use of the Bunsen burner is introduced in unit 7I ‘Energy resources’. If pupils have not done this unit, they will need to be shown how to use a Bunsen burner

– handle crystals with forceps

– remind pupils that some things remain hot even if they do not look hot

– take care with sharp edges on glass or metal blocks

– use eye protection when adding weights to a thin wire and make sure feet are well out of the way of falling weights

– make sure pupils know what to do if something catches fire

   KS3 Biology: How are theories created?

   to share and discuss ideas

   that theories are based on experimental data

   that sometimes new evidence results in changes to theories

   Introduce the idea that scientists collect data or evidence and that they try to think creatively to explain this evidence. Theories result from scientists relating their ideas to the evidence and refining their ideas.

   Present pupils with a game or puzzle to play, eg a murder mystery game, where each group is given some evidence about an event, eg a fictitious murder, and is asked to establish what happened on the basis of the evidence.

   Provide further evidence, which could be given part-way through, to encourage pupils to modify their original suggestion on the basis of the new evidence. Ask pupils to reflect on their ideas, to explain why they arrived at their first conclusion, and what caused them to change their ideas.

  evaluate the ideas of others and collectively create a solution to the game/puzzle which is consistent with the evidence

  explain how their solution is consistent with the evidence and, if necessary, why they had to change their ideas

   The purpose of this activity is to help pupils see that data and theory relate. They will also see that it is often difficult to suggest theories that fit the data.

   KS3 Biology: What are the differences between solids, liquids and gases?

   that materials can be classified as solid, liquid or gas, but that some are difficult to classify

   to evaluate their own theory in the light of evidence

   Give pupils a range of materials to classify as solid, liquid or gas. Include some materials that pupils find difficult to classify, eg paper, sand, jelly, talc, toothpaste, tomato sauce, reusable adhesive, etc. Tell pupils they should be prepared to justify their classification, making explicit the criteria they used. Ask them to list the properties of solids, liquids and gases and use this to develop a key for classifying materials.

   Ask pupils to imagine they can see what the materials are made from by using an immensely powerful microscope and, in groups, to discuss and create their own theory or model of what the materials are made from. Invite pupils to communicate these to the class. At this stage, help pupils identify inconsistencies between theory and evidence, but do not give the correct particle theory.

  classify materials and justify their classification in terms of properties of solids, liquids and gases

  explain why some materials are difficult to classify

  generate descriptions of solids, liquids and gases consistent with the evidence and their scientific knowledge, eg a solid is made of tiny grains all glued together

  design a key to classify materials as solid, liquid or gas

   This activity is familiar from key stage 2. The emphasis here is on pupils deciding the criteria for classification, thinking about whether these can be used in the cases they have and, if necessary, amending or refining their criteria.

   One group may classify one substance as solid, while another may say it is liquid; this provides a good discussion point about the limitation of the solid/liquid/gas system for classifying and the need for clear criteria.

   Many pupils will already have heard of particles; they may use terms for them, eg atom, molecule, perhaps incorrectly.

   Some may confuse microbes, cells and particles and the differences will need to be made explicit (see unit 7A ‘Cells’).

   KS3 Biology:  How can the particle model explain the differences between solids, liquids and gases?

   that models can be used to explain phenomena which cannot be observed

   that sometimes new evidence requires changes to models

   that solids, liquids and gases are made up of tiny particles

   that the differences between solids, liquids and gases can be explained in terms of the proximity and motion of their particles

   Using a variety of media, eg simulation software, three-dimensional models, diagrams, texts, modelling using pupils, make explicit to pupils the accepted theory about particles in terms of their proximity and motion.

   Through discussion and questioning, establish the similarities and differences between their theories and the accepted one and show how the accepted one explains the evidence.

  describe in writing and drawing the arrangement, proximity and motion of particles in solids, liquids and gases

  describe how particle theory can explain some phenomena, eg diffusion of a gas, mixing of liquids, expansion of a metal bar

   At this stage it is important to establish the key ideas of particle theory with pupils. It may be helpful to point out that these ideas were established gradually over a long period of time, and that some scientists once had ideas similar to some of the pupils’ ideas and had to modify them.

    KS3 Biology: How can the particle model explain other phenomena?

   to apply a model to new phenomena to explain behaviour

   how discussion can help clarify ideas

   Invite pupils to carry out additional quick experiments in groups, eg

placing coloured crystals on agar gel and observing the diffusion of colour

placing distinct layers of water and ink in plastic syringes and observing the mixing of colour over a short period of time

– observing dust particles in a beam of light

   Ask them to try to explain their observations using knowledge and understanding about particles, discussing their ideas with each other. Explain that they must check that the explanations they will give to the class later include use of the particle theory.

  explain observations in terms of particles

  evaluate their own explanations and those of others

   This work could be available over a period of time to allow pupils the opportunity to assimilate and apply particle theory. The specific phenomena used are not important provided they allow pupils to practise applying their knowledge.

   In unit 7H ‘Solutions’, pupils consider what happens when solids dissolve in liquids. This will provide them with further opportunities to apply and consolidate their knowledge.

Safety 

use forceps for handling crystals and choose those that can be handled safely

   that gas particles are moving around all the time

   that gas pressure is caused by particles hitting the walls of the container

   Give pupils access to all the experiments they had at the start of the unit and ask groups to present explanations using particle models, eg orally or using flip charts, OHPs.

   Demonstrate that gases mix by diffusion, eg by mixing bromine and air, or nitrogen dioxide and air, or allowing gas jars of hydrogen and air to mix. Use a range of methods, eg video clips, simulation software, pupils modelling, to illustrate the movement of gas particles and explain diffusion.

   Discuss with pupils the idea of air particles all around before demonstrating the collapsing can experiment. Ask pupils, in groups, to explain why the can collapses; link their ideas back to pressure of gas inside and outside the can.

  explain their observations using the particle theory

  identify where there are contradictions in their ideas, when these are pointed out

  describe gas particles as moving all the time and pushing against surfaces

  explain that the can collapses because there are fewer air particles on the inside pushing out than on the outside
pushing in

   Pumping air out of a can works well and helps pupils to focus on air inside and outside the container. Many pupils explain the collapse of the can in terms of air being sucked out rather than in terms of movement of molecules.

   Pupils will have opportunities to revisit diffusion in unit 8F ‘Compounds and mixtures’ and unit 9L ‘Pressure and moments’.

Safety

bromine and nitrogen dioxide are toxic and corrosive. Employer’s risk assessments must be followed

 KS3 Biology: Reviewing work

   how to make notes and summaries to clarify ideas

   to summarise the particle theory in writing and drawing

   Ask pupils to make annotated drawings to describe the arrangement and movement of particles in solids, liquids and gases. Ask them to choose two of the experiments they have carried out, or have seen, and describe what they did, what they observed and to explain their observations in terms of the particle theory.

  draw and describe particles in solids, liquids and gases in terms of the movement and proximity of their particles

  describe observations they have made and explain them, eg a metal block is heavier than a wooden block because the particles are heavier or because the particles are closer together

   Many pupils will need more time and practice to grasp these ideas. They are revisited in many units – see ‘Where the unit fits in’ at the beginning of this unit.

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry - KS3 SCIENCE Unit 7H Solutions


KS3 Chemistry In this unit you should learn to ...

  • extend your knowledge of dissolving and the separation of the components of a solution and relate this to particle theory
  • begin to distinguish between a ‘pure’ substance and a mixture
  • apply the particle model of solids, liquids and gases in a range of contexts
  • make measurements of temperature and mass
  • describe and interpret patterns in graphs and chromatograms
  • make predictions from graphs and data about solubility
  • investigate, and explain, how a sample of pure salt can be obtained from a sample of rock salt, evaluating the method in terms of salt obtained
  • classify some solids as soluble or insoluble and explain the meaning of the term ‘urated solution’
  • describe how mixtures can be separated by distillation and chromatography
  • use the particle model to explain what happens when a solid dissolves in water, explaining why mass is conserved

Its handy if you ...

  • have had experience of dissolving solids in water and know that not all are soluble
  • have separated mixtures of solids and liquids
  • know that not all liquids contain water
  • know that all materials are made up of very small particles

Some important words for you to understand, use and spell correctly ...

  • words and phrases relating to dissolving, eg solution, solute, solvent, soluble, insoluble, saturated solution
  • words and phrases relating to the separation of mixtures, eg filtration, distillation, chromatography, chromatogram
  • words and phrases relating to explanations using the particle model, eg particle, attracted, mixing, mingling
  • words and phrases relating to scientific enquiry, eg prediction, evaluate, interpret
  • words with similar spelling but different meanings, and use them in a consistently correct way, eg affect, effect

How can we tell whether a liquid is a mixture?

  • that some solids dissolve in liquids and others do not
  • that many common materials are mixtures and mixtures can be separated
  • selection of liquids, eg distilled water or deionised water, seawater, a suspension of chalk in water, ethanol, copper sulphate solution, and ask is it water? is it pure?
  • devise techniques, eg filter, evaporate to dryness, to find out whether a liquid is a mixture or not
  • learn the terms ‘soluble’, 'solvent', 'solution‘, 'insoluble’ and ‘solute’
  • name some solids that dissolve in water and some that do not
  • identify the components of some mixtures, eg seawater is water with salt and other solids dissolved in it

How much salt can we get from rock salt?

  • use knowledge about separating mixtures to obtain a sample of salt from rock salt
  • that salt comes from a variety of sources and has many uses
  • although the salt dissolves, it doesn’t disappear!
  • the occurrence, extraction and uses of salt - relate this to processes used in the laboratory
  • explain why the mass of the salt sample was less than the mass of rock salt

What happens to the solute when a solution is made?

  • that when a solute dissolves, mass is conserved
  • that when a solute dissolves, the solute and solvent particles intermingle
  • draw the water particles (solvent) before and after the addition of salt (solute) and use this to explain, eg that mass is conserved, or why filtering will not separate the salt
  • mixing two liquids, eg ethanol and water or oil and water - which mix/dissolve in each other?

How can we separate solvents from solutes?

  • distillation can be used to separate a liquid from the solids which are dissolved in it eg ink solution
  • distillation is a process in which evaporation/boiling of a liquid is followed by condensation by cooling
  • it is often very important to separate and collect the liquid, eg in purifying water.
  • how they could you obtain drinkable water from seawater?, eg in an area where there is a lot of seawater, but no fresh water.
  • describe how the solvent could be separated from the solute by distillation
  • distillation separation works because the solvent changes to a gas and back to a liquid, but the solute does not evaporate
  • find out about desalination plants or how distillation is used to separate liquids, eg crude oil.

How can chromatography separate and identify substances in mixtures?

  • that a mixture of two or more solutes which are soluble in a particular solvent can be separated and identified by chromatography
  • how to separate the different coloured compounds in an ink mixture on blotting or filter paper, using a wick of the paper dipped into the solvent (water).
  • why do different coloured ink solids travel different distances?
  • use particle ideas to explain how chromatography works
  • find out at home whether food or sweet colourings, inks in felt-tip pens or markers are single dyes or mixtures of dye.
  • how chromatography can be used to compare mixtures of solutes
  • how scientists use evidence from chromatography - forensic science, medical analysis
  • chromatography can be used with non-coloured solutes - but you need to make the different solutes 'show up' in some way eg add a chemical that makes them coloured or shine on ultra-violet light to make them 'glow'

Is there a limit to the amount of solid that will dissolve in a liquid?

  • when a solid is added to a liquid, eventually no more will dissolve (a saturated solution) - there is limit to how much can dissolve in a particular volume of solvent - how can you tell no more dissolves?
  • that different masses of different solids dissolve in the same volume of a particular solvent
  • that solids can dissolve in liquids other than water
  • state that some solids dissolve more in some liquids than others - different solvents, different solubility

What else affects solubility?

  • that many solutes are more soluble at higher temperatures
  • you can use tables of data to calculate quantities of material to use
  • to make comparisons, identify patterns and make predictions from graphs
  • cooling a saturated solution, eg of benzoic acid, which forms crystals as it cools.
  • state that a saturated solution has been formed when crystals appear
  • state the solubility at a particular temperature, eg at 70°C, 3g of the solid dissolved in 100g of water
  • it is important to draw the distinction between dissolving in terms of  ‘how much’ and ‘how fast’.

KS3 Chemistry About the unit

In this unit pupils:

  extend their knowledge of dissolving and the separation of the components of a solution and relate this to particle theory

  begin to distinguish between a ‘pure’ substance and a mixture

  apply the particle model of solids, liquids and gases in a range of contexts

In scientific enquiry pupils:

  make measurements of temperature and mass

  describe and interpret patterns in graphs and chromatograms

  make predictions from graphs and data about solubility

  investigate how a sample of pure salt can be obtained from a sample of rock salt, evaluating the method in terms of salt obtained

KS3 Chemistry Where the unit fits in

This unit develops work on solids, liquids and separating mixtures in the key stage 2 programme of study. It builds on unit 4D ‘Solids, liquids and how they can be separated’, unit 5C ‘Gases around us’, unit 5D ‘Changing state’, unit 6C ‘More about dissolving’ and unit 6D ‘Reversible and irreversible changes’ in the key stage 2 scheme of work.

The unit builds on ideas introduced in unit 7G ‘Particle model of solids, liquids and gases’.

Pupils will have many opportunities in later units to try to explain phenomena in terms of particles, eg changes of state in unit 8I ‘Heating and cooling’, digestion in unit 8A ‘Food and digestion’, crystal size related to rate of cooling in unit 8H ‘The rock cycle’, the behaviour of gases in unit 9L ‘Pressure and moments’.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: make measurements of temperature and mass; present experimental results as line graphs, pointing out patterns; describe observations and explain these; identify patterns in data about solubility, and make predictions from these; interpret data from chromatograms; use scientific knowledge and understanding to plan how to separate pure salt from rock salt

some pupils will not have made so much progress and will: make measurements of temperature and mass; produce simple line graphs of results and point out patterns in these; separate a sample of salt from rock salt

some pupils will have progressed further and will: make measurements of temperature and mass; interpret and explain the significance of data from chromatograms; evaluate their method for obtaining pure salt in terms of the mass obtained

in terms of materials and their properties

most pupils will: classify some solids as soluble or insoluble and explain the meaning of the term ‘saturated solution’; describe how mixtures can be separated by distillation and chromatography and begin to use the particle model to explain what happens when a solid dissolves in water, explaining why mass is conserved

some pupils will not have made so much progress and will: name some soluble and insoluble solids; describe how pure water can be obtained from sea water and how different colours can be separated from some inks

some pupils will have progressed further and will: use the particle model to explain a range of phenomena

KS3 Chemistry Prior learning

 It is helpful if pupils:

  have had experience of dissolving solids in water and know that not all are soluble

  have separated mixtures of solids and liquids

  know that not all liquids contain water

  know that all materials are made up of very small particles

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  plan and carry out an investigation of their own

  use highly flammable and harmful substances

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words and phrases relating to dissolving, eg solution, solute, solvent, soluble, insoluble, saturated solution

  words and phrases relating to the separation of mixtures, eg filtration, distillation, chromatography, chromatogram

  words and phrases relating to explanations using the particle model, eg particle, attracted, mixing, mingling

  words and phrases relating to scientific enquiry, eg prediction, evaluate, interpret

  words with similar spelling but different meanings, and use them in a consistently correct way, eg affect, effect

KS3 Chemistry Resources

Resources include:

  prepared data about:

    – the solubility of different solids in water

    – the solubility of solids in different solvents

    – the variation of solubility of solids in water with temperature (as tables and graphs)

  chromatograms for interpretation

  software simulation of particles in mixtures

  secondary sources showing uses of chromatography, eg caffeine determination in drinks, identifying traces of photoallergens (causing irritation) in germicides and soaps, identification of sugars in urine, identification of traces of drugs in horses

KS3 Chemistry Out-of-school learning

Pupils could:

  find out where distilled water is used and about other uses of distillation

  look at labels of household liquids to find out whether they are pure liquids or mixtures

    KS3 Biology: How can we tell whether a liquid is a mixture?

   that some solids dissolve in liquids and others do not

   that many common materials are mixtures

   that mixtures can be separated

   Present pupils with a selection of liquids, eg distilled water or deionised water, seawater, a suspension of chalk in water, ethanol, copper sulphate solution, and ask pupils about them, eg Is it water? Is it pure? Ask pupils to describe work they did on solutions and on separating solids from liquids in key stage 2. Challenge them to devise techniques, eg filter, evaporate to dryness, to find out whether the liquid is a mixture or not. Ask them to record their observations and explain what their method showed. Help the class to summarise different approaches used and introduce the terms ‘soluble’, ‘insoluble’ and ‘solute’.

  name some solids that dissolve in water and some that do not

  identify the components of some mixtures, eg seawater is water with salt and other solids dissolved in it

  describe one way of separating the components of a mixture

   This activity is designed to find out what pupils already know about solid/liquid separation. In the light of this, teachers may wish to put more emphasis on making mixtures and separation techniques with some pupils and on particle explanations with others.

   Extension: pupils could investigate the labels on packaging of household items and food to find out which are mixtures and which are not.

Safety

teachers will need to check pupils’ plans for health and safety before practical work begins. Ethanol is highly flammable, so there should be no naked flames in the room if ethanol is used. Copper sulphate solution is harmful if the concentration is greater than
1.0 mol dm
-3
. Eye protection should be worn

   KS3 Biology:  How much salt can we get from rock salt?

   to use knowledge about separating mixtures to obtain a sample of salt from rock salt

   to evaluate methods used in terms of the mass of salt obtained

   that salt comes from a variety of sources and has many uses

   Present pupils with a sample of rock salt and say that pure salt can be obtained from this. Ask them to plan a way of obtaining a sample of pure salt. Extend this for some pupils by asking them how they could find out how much of their rock salt is pure salt and to compare their results with those of others. Ask pupils to produce an account of what they did, describing and explaining each stage. Emphasise that, although the salt dissolves, it doesn’t disappear.

   Show a video about the occurrence, extraction and uses of salt. Relate this to the processes pupils have used in extracting their sample.

  plan a method for obtaining a sample of salt from rock salt

  obtain a sample of salt

  explain why the mass of the salt sample was less than the mass of rock salt

  explain in terms of the original sample or in terms of techniques why results of different groups differ

   The activity could be set in the context of comparing the salt content of different rock salts used on icy roads in winter, or of comparing the efficiency of different pupils’ methods of obtaining a sample of salt.

   Extension: pupils could be asked to use secondary sources to find out more about salt, eg its importance in diet and possible hazards, sources and history of use.

Safety

– teachers will need to check pupils’ plans for health and safety before practical work begins

– pupils should not taste the salt after it has been purified

     KS3 Biology: What happens to the solute when a solution is made?

   that when a solute dissolves, mass is conserved

   that when a solute dissolves, the solute and solvent particles intermingle

   Show pupils a beaker of water of a particular mass, eg 100g, and ask them to predict what the total mass will be if some salt, eg 4g, is dissolved in the water, and to test their predictions by weighing. Ask them to explain why the mass remains the same and to say how much salt they would expect to get if they evaporated the water.

   Remind pupils of work they did on particles in solids and liquids in unit 7G ‘Particle model of solids, liquids and gases’, referring back to the annotated diagrams drawn at the end of the unit.

   Show a model or models, eg ICT simulation, mixing rice and peas, to illustrate the mixing of particles when a solid dissolves in a liquid, asking pupils to put in their own words what is happening.

   Ask pupils to draw the water particles before and after the addition of salt and to use these to explain, eg that mass is conserved, why filtering will not separate the salt.

  state that the mass of a solution is the same as the mass of the solute and solvent, eg if you dissolve 5g of salt in 200g of water, you’ll get 205g of salt solution

  describe, eg using annotated diagrams, how solute and solvent particles mix

  explain that as the particles mix no matter is lost, so the mass remains the same

   Extension: some pupils could explore mixing two liquids, eg ethanol and water.

   In unit 7K ‘Forces and their effects’ pupils are introduced to the difference between mass and weight and to the use of balances.

Safety

ethanol is highly flammable, so there should be no naked flames in the room when it is being used

  KS3 Biology:   How can we separate solvents from solutes?

   that distillation can be used to separate a liquid from the solids which are dissolved in it

   that distillation is a process in which evaporation of a liquid is followed by condensation

   Explain to pupils that work so far has concentrated on the solute in a mixture but that it is often very important to separate and collect the liquid, eg in purifying water.

   Remind pupils of work done on evaporation and condensation at key stage 2, eg by showing them a sample of blue ink and asking them to predict the colour of the water obtained when it was evaporated and then condensed. If necessary, carry out a quick demonstration. Ask them how they could obtain drinkable water from seawater, eg in an area where there is a lot of seawater, but no fresh water. Discuss pupils’ ideas with them and introduce the term ‘distillation’. Help pupils to test their ideas by carrying out a simple distillation process.

   Ask pupils to explain the process, eg by using a flow chart, annotated drawing.

  describe how the solvent could be separated from the solute by heating the solution, followed by cooling

  explain that separation works because the solvent changes to a gas and back to a liquid, but the solute does not

   In key stage 2, pupils are likely to have seen colourless water collected from the evaporation of blue ink.

   Extension: pupils could be asked to find out about desalination plants or how distillation is used to separate liquids, eg crude oil. At this stage it is not necessary to draw distinctions between distillation and fractional distillation.

Safety  

teachers should check pupils’ plans for health and safety before practi­cal work begins. Pupils should be taught safe procedures for using glassware and fitting bungs into it

    KS3 Biology: How can chromatography separate and identify substances in mixtures?

   that a mixture of two or more solutes which are soluble in a particular solvent can be separated by chromatography

   to separate and identify materials using chromatography

   Remind pupils of work they did earlier on showing whether a liquid was pure or not. Explain that they are going to explore some other techniques for this.

   Demonstrate how to separate the different coloured compounds in an ink mixture on blotting or filter paper, using a wick of the paper dipped into the solvent (water). Discuss and establish with pupils why different coloured ink solids travel different distances, perhaps using the analogy of the solvent particles giving the solute particles ‘piggyback rides’, so those which attach more firmly to the solvent particles can be carried further than those which do not, in a given amount of time.

  use chromatography to separate and identify different solutes

  use particle ideas to explain how chromatography works

   Extension: pupils could be asked to find out at home whether food colourings, inks in felt-tip pens or markers are single dyes or mixtures of dye.

Safety  

– if solvents other than water are used, pupils should be taught to handle them safely

   how chromatography can be used to compare mixtures of solutes

   how scientists use evidence from chromatography

   Ask pupils to use chromatography to compare the components of dyes, eg the colouring on sugar-coated chocolate sweets, to find out whether different colours include the same dyes and to explain what they found, eg using drawings and annotated diagrams. Extend by providing pupils with prepared chromatograms and information about the contexts in which these might be needed, eg in forensic science, in identifying traces of substances in urine or medical preparations, and asking them to interpret the evidence from each chromatogram.

  interpret chromatograms, explaining what the evidence shows

  describe a situation in which chromatography provides useful evidence 

   Many pupils think that chromatography can only be used with coloured solutes.
It is helpful to illustrate how chromatography is used with non-coloured solutes.

    KS3 Biology: Checking progress

   how particle theory can be used to model changes that take place when solutions are formed or components of solutions are separated

   Use ICT simulation to show pupils how to model a change, eg some solid dissolving in water, by representing the particles themselves, making sure that those representing the solid are clearly distinguishable from those representing the water. Ask groups of pupils to work out how to model other changes, eg adding an insoluble solid to water, the formation of a suspension, separation by chromatography of two solutes, the evaporation of a solution. Help pupils to write a brief description of each change.

  show by modelling how particles behave in some changes

  describe what the models show, eg when marble is added to water it doesn’t break up into smaller particles, so the particles can’t mix together

   At this stage it is not necessary to distinguish between atoms and molecules.

    KS3 Biology: Is there a limit to the amount of solid that will dissolve in a liquid?

   that when a solid is added to a liquid, eventually no more will dissolve

   that different masses of different solids dissolve in the same volume of a particular solvent

   that solids can dissolve in liquids other than water

   Present some pupils with a selection of solids, eg salt, bicarbonate of soda, potassium nitrate, and ask them how they could find out whether there is a limit to how much will dissolve in water at room temperature. Ask other pupils to find out whether there is a limit to the amount of solid, eg salt, that will dissolve in different liquids, eg water, ethanol. Discuss with them how they will decide when no more dissolves and suggest that different groups use different volumes of solvent. Bring together results for the same solvent and look for patterns in these. Introduce the terms ‘saturated solution’ and ‘solubility’.

  state that there is a limit to the amount of solid that dissolves in a particular volume of water

  describe differences between the amounts of different solids that dissolve in the same volume of water

  state that some solids dissolve more in some liquids than others

   It is important to clarify with pupils that they are finding out how much of something dissolves, not how fast it dissolves. They are likely to have investigated the latter at key stage 2.

Safety

– ethanol is highly flammable,
potassium nitrate is oxidising. Teachers should make sure pupils can handle these and other substances carefully. This activity is not intended to explore variation in solubility with temperature and there is no need to heat the solvents

     KS3 Biology: What else affects solubility?

   that many solutes are more soluble at higher temperatures

   to use tables of data to calculate quantities of material to use

   to make comparisons, identify patterns and make predictions from graphs

   Ask pupils to suggest what else affects how much solid dissolves in a liquid, perhaps showing them a saturated solution, eg of benzoic acid, which forms crystals as it cools. Provide pupils with a table of data showing approximate solubilities of solutes at different temperatures. Help them to work out how much they would need to dissolve in 10g of water to make a saturated solution at a particular temperature. Ask pupils to prepare a warmed solution with a suitable amount of solid and to cool it down to identify the temperature at which crystals appear. Put together class results and help pupils to draw a graph showing how solubility varies with temperature and to describe what the graph shows and what the solubility might be at other temperatures.

  state that a saturated solution has been formed when crystals appear

  state the solubility at a particular temperature, eg at 70°C, 3g of the solid dissolved in 10g of water

  describe the way in which the solubility of the solute varies with temperature

  use the pattern of solubility data to predict solubility at higher and lower temperatures

   Pupils are likely to have used a variety of thermometers in key stage 2 and this is extended in unit 7I ‘Energy resources’.

   As in the previous activity, it is important to draw the distinction between ‘how much’ and ‘how fast’.

   This activity works well using potassium chloride, potassium bromide or potassium iodide as the solute.

   Extension: pupils could look at previously prepared data about the variation of solubility with temperature of a wider range of solutes, and identify simple patterns and make predictions from these.

Safety

– remind pupils how to heat test tubes of chemicals

  KS3 Biology: Reviewing work

   to identify key points about changes involving making and separating solutions

   to explain changes and techniques

   Provide pupils in groups with two sets of cards: each card in one set has the name of a change or technique, each card in the other set has the explanation of a change or technique. Ask them to match the correct explanation to the change or technique. For some pupils increase the range of changes, including some incorrect explanations to encourage discussion and deeper thinking about the phenomena.

   Ask pupils to work in groups and list the key ideas about the changes, including two examples of each. Ask them for their ideas and discuss the changes, emphasising that those encountered in this unit can be relatively easily reversed. Together with pupils agree a summary of the unit.

  match the correct explanation to each change

  identify, with reasons, incorrect explanations

  summarise key points about changes and techniques in the unit

   Unit 8E ‘Atoms and elements’ introduces the idea of chemical change as changes in which atoms are joined in new ways, making new materials.

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry - KS3 SCIENCE Unit 8E Atoms and elements


KS3 Chemistry In this unit you should learn ...

  • that the huge range of materials is made from a relatively small number of elements
  • that each element is composed of one sort of atom only
  • the characteristics of some elements
  • to use particle models to describe what happens when elements combine to form compounds
  • how to find out whether a substance is an element or not
  • how to deal with hazards when preparing oxides
  • different elements and compounds show a variety of properties 

Its handy if you ...

  • understand the differences between solids, liquids and gases
  • have seen and described changes of state
  • know how particle models can be used to explain things

Some important words for you to understand, use and spell correctly

  • scientific words, eg element, compound, atom, molecule, symbol, formula
  • names of elements and compounds, eg oxygen, carbon dioxide, sodium, chlorine, sodium chloride
  • words and phrases with different meanings in scientific and everyday contexts, eg element, equation, state

How many different materials are there?

  • there is a huge variety of materials
  • there is a small number of elements from which all other materials are made
  • there are approximately 100 elements and that these are the building blocks of all materials
  • name a wide variety of materials, huge numbers are known, many more will be made!
  • describe elements as the materials from which everything else is made
  • gases, eg chlorine, are also materials
  • many, but not all, elements are metals and for the moment classify materials simply as ‘metals’ and ‘other elements’ or ‘metals’ and ‘non-metals’

What are elements made from?

  • to distinguish between elements and other materials
  • that each element is made up of one sort of particle and these are called atoms
  • everything in the universe is made out of a limited number of building blocks, but the diversity of things is determined by the ways in which these blocks are assembled (blocks means the atoms of elements)
  • if you take a piece of element, eg aluminium or carbon, and pull its particles apart like the bricks, you would end up with a pile of the smallest particles of the element that can exist and scientists call this particle an atom.
  • introduction to the idea of a chemical symbol representing an element, eg by displaying some samples of elements with the symbols attached and recognise the symbols for some elements, the symbol represents an atom of the element

What are elements like?

  • that elements vary in their appearance and state eg metal, non-metal, appearance, magnetic, physical state at room temperature, melting point etc.
  • questions about the periodic table  eg Where are the metals? How many elements are gases/liquids?
  • the periodic table shows all the elements and that similar elements are grouped together
  • describe some differences between elements
  • make some generalisations about elements, eg there are more metals than non-metals; most metals are non-magnetic

How do we get all the other materials?

  • that new materials are formed when atoms join together in different ways
  • that compounds are formed when different atoms combine
  • that atoms can combine to form molecules, which can be elements or compounds
  • using the terms ‘molecule’ and ‘compound’, using models or diagrams, of simple and more complicated molecules
  • looking at samples of compounds and their formulae.
  • describe compounds, eg water is made of hydrogen and oxygen joined together
  • describe some simple molecules, eg carbon dioxide is made of one carbon atom joined to two oxygen atoms

How can we represent the changes when new materials are made?

  • that atoms of elements combine to form molecules of compounds
  • that in chemical changes new substances are formed
  • represent and explain chemical reactions by word equations, models or diagrams
  • some reactions between elements, eg hydrogen and oxygen; sodium and chlorine; carbon and oxygen; copper and sulphur an
    • make observations in terms of the appearance of the reactants and the products
    • to represent the reactions by word equations, simulation software, particle models or diagrams
    • when the compound is formed the atoms join
  • extend by showing that the compound (and molecule) water can be split into its elements hydrogen and oxygen by electrolysis.
  • to predict what might be formed from a chemical reaction between elements eg zinc oxide from zinc and oxygen, iron sulphide from iron and sulphur
  • to heat metals in air safely e.g. what happens when magnesium ribbon or copper foil is heated strongly in air to form oxides
  • interpret the names and/or formulae of binary compounds in terms of the elements of which they are composed
  • it is not true that all chemical reactions involve elements as reactants and compounds as products, later you will look at elements or compounds, reacting with compounds
  • practise using the chemical names of compounds, eg making the change from oxygen to oxide.
  • become familiar with some formulae for common compounds and to relate these to models showing the numbers of atoms

KS3 Chemistry About the unit

In this unit pupils:

  learn that the huge range of materials is made from a relatively small number of elements

  learn that each element is composed of one sort of atom only

  explore the characteristics of some elements

  use the particle model to describe what happens when elements combine

In scientific enquiry pupils:

  model differences between particles in elements and non-elements

  organise and sequence information from secondary sources

  choose an approach to find out whether a substance is an element or not

KS3 Chemistry Where the unit fits in

This unit relates closely to unit 7G ‘Particle model of solids, liquids and gases’ and unit 7H ‘Solutions’, in which the particle model is introduced and developed. However, if teachers wish to introduce the idea of particles through elements and compounds, it could be taught before these units.

The unit provides a foundation for unit 8F ‘Compounds and mixtures’, unit 9E ‘Reactions of metals and metal compounds’ and unit 9F ‘Patterns of reactivity’.

The historical impact of ideas about  atoms is covered in unit 21 ‘Scientific discoveries’ in the history scheme of work

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: select information about elements and their properties from a range of secondary sources; describe how to deal with hazards when preparing oxides; identify an approach to finding out whether a material is an element or not and explain how their results provide appropriate evidence

some pupils will not have made so much progress and will: find information from selected secondary sources about elements and their properties; describe some hazards in preparing oxides and describe the results of their investigations

some pupils will have progressed further and will: select secondary sources to provide the information needed about elements and their properties; identify limitations of evidence obtained about whether a substance is an element or not, where appropriate, suggesting alternative explanations

in terms of materials and their properties

most pupils will: recognise that there is a small number of elements and name some of these; explain that compounds are made when atoms of different elements join together; begin to use symbols for elements and to represent reactions in word equations

some pupils will not have made so much progress and will: name some elements and represent these by symbols; distinguish between symbols for elements and formulae for compounds; name a wide variety of materials

some pupils will have progressed further and will: identify elements whose properties do not fit the general pattern of metals and non-metals; begin to represent compounds by formulae

KS3 Chemistry Prior learning

It is helpful if pupils:

  understand the differences between solids, liquids and gases

  have seen and described changes of state

  know how models can be used to explain phenomena

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  observe reactions of a variety of elements

  plan and carry out an investigation of copper carbonate

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  scientific words, eg element, compound, atom, molecule, symbol, formula

  names of elements and compounds, eg oxygen, carbon dioxide, sodium, chlorine, sodium chloride

  words and phrases with different meanings in scientific and everyday contexts,
eg element, equation, state

  words relating to scientific enquiry, eg data search, predicting products of reactions

Through the activities pupils could:

  discuss and question what they are learning

  undertake independent research using knowledge of how texts and databases are organised and of appropriate reading strategies

KS3 Chemistry Resources

Resources include:

  model-building-brick system

  a collection of materials, including biological materials, eg leather, bone, wood

  access to information sources, eg CD-ROM, internet, data books, which can be searched

  paper/card cubes or thick paper from which cubes can be made

  large periodic table which can be placed on a table or floor

  individual copies of the periodic table for pupils

  copies of pupils’ periodic tables in other languages

  samples or photographs of a wide variety of elements

  models, or photographs of models, of a range of molecules, including very large structures, eg DNA and enzymes

  software simulations of chemical reactions

KS3 Chemistry Out-of-school learning

Pupils could:

  ask grandparents and other older people about materials that were used for clothing and utensils before plastics and synthetic fibres became so widely available

 KS3 Chemistry: How many different materials are there?

   that there is a huge variety of materials

   that there is a small number of elements from which all other materials are made

   Show pupils a collection of elements and materials of different kinds, including some elements, some living things and some rock samples, to illustrate the huge variety of materials that exists. Ask pupils to suggest names of other materials. List a number of these, separating out any elements mentioned, and ask pupils to suggest why these have been listed separately. Introduce the termelement’. Ask pupils to suggest names of other elements and explain that in this unit they will be finding out why elements are important and how they are different from other materials. Establish with pupils that there are approximately 100 elements and that these are the building blocks of all materials. Point out that we can’t possibly count the number of materials that can be made from them.

  name a wide variety of materials

  describe elements as the materials from which everything else is made

   It is helpful to include gases, eg chlorine, in the collection so pupils recognise these as materials.

   At key stages 1 and 2 pupils will have begun to distinguish between an object and the material from which it is made. Some pupils will continue to need help with this.

   Some pupils are likely to be familiar with the word ‘element’. It may be helpful to point out that many, but not all, elements are metals and to classify materials simply as ‘metals’ and ‘other elements’ or ‘metals’ and ‘non-metals’ at this stage.

Safety  

elements that are hazard­ous, eg chlorine, bromine, sodium, can be used as sealed samples if the teach­er keeps careful control

 KS3 Chemistry: What are elements made from?

   to distinguish between elements and other materials

   that each element is made up of one sort of particle and these are called atoms

   that models can be used to illustrate phenomena that cannot be observed

   Use a model-building-brick system to show that there is a limited number of types of brick out of which everything can be made. Explain that we believe that everything in the universe is made out of a limited number of building blocks, but the diversity of things is determined by the ways in which these blocks are assembled.

   Model elements and other materials by showing pupils structures or materials made of only one kind of brick and others made of several. Ask them to decide and explain which are like elements and which are not.

   Take some objects made of only one type of brick and pull them apart until they can’t be pulled apart any more. Explain to pupils that if you take a piece of element, eg aluminium or carbon, and pull its particles apart like the bricks, you would end up with a pile of the smallest particles of the element that can exist. Scientists call this particle an atom.

   Check pupils’ understanding that elements are made of one kind of particle only by asking them to draw pieces of a few named elements, then draw the individual atoms after the element pieces have been pulled apart as much as possible. Ask pupils to label the atoms and the elements and write about what the two words mean in science. Extend to models of non-elements.

   Introduce the idea of a chemical symbol representing an element, eg by displaying some samples of elements with the symbols attached.

  show by their drawings that they have some understanding of the relationship between elements and atoms and between elements and non-elements

  recognise the symbols for some elements

   Throughout this unit it may be helpful to emphasise that classification of materials is a way of making sense of the wide variety that exists.

   It is important that pupils realise it is a material, and not an object, that is being modelled. Teachers could use other models, eg atom/molecule kits, models of crystal structure, ICT simulations, as alternatives or additions.

   Many pupils will not arrive at the correct understanding about elements and atoms immediately. It may be helpful to make it explicit to pupils that these ideas become clear as they use and become more familiar with them.

   Some teachers may wish to introduce the idea that the symbol represents one atom of the element, but others will not feel it necessary at this stage.

   Teachers may wish to explore some of the limitations of the model with some pupils, eg you can build many ‘materials’ from one size of red brick, but one type of atom forms one element.

 KS3 Chemistry: What are elements like?

   to undertake independent research using knowledge of how texts and databases are organised and of appropriate reading strategies

   that elements vary in their appearance and state

   Make clear to pupils that they are each going to find out about some elements using secondary sources of information, eg CD-ROM, internet, data books, and that the information they collect will be used by the whole class to get a picture of what many of the 100 or so elements are like.

   Give groups of pupils the names of around five elements and ask them to search for the following data on each element:

    – its symbol

    – its state at 20°C

    – whether it is described as a metal or a non-metal

    – whether it is described as magnetic or not

    – its appearance

    – any other information they might think important

   Ask pupils to transfer these six pieces of information onto the six sides of a cube, colour-coded for: symbol; metal/non-metal; solid/liquid/gas; magnetic/non-magnetic; appearance; other information. Where possible, show pupils samples or photographs of the elements so that they can compare them with their research. Show pupils a periodic table and ask them to arrange their cubes according to the arrangement of the periodic table, with each face uppermost in turn. Ask pupils to answer a series of questions, eg Where are the metals? How many elements are gases/liquids? Explain that the periodic table shows all the elements and that similar elements are grouped together.

  locate and record the required information, eg complete the six faces of the cube

  describe some differences between elements

  make some generalisations about elements, eg there are more metals than non-metals; most metals are non-magnetic

   Pupils will need to be shown how to search the internet for the information they need, and how to select from all the information the key points you want them to focus on. They should be encouraged not to record anything they do not understand.

   Many websites contain information about elements, eg

    – www.shu.ac.uk/schools/sci/chem

    – www.knowledgebydesign.com/tlmc /tlmc.html

    –www.chemsoc.org/viselements /pages/data/

    – www.sciquest.com/

   At this stage it is not necessary to go into detail about how elements are arranged in the periodic table, although some teachers may wish to do so with some pupils.

   Extension: pupils could be allocated a particular element and asked to find out interesting information about it and to contribute to a class display about elements.

 KS3 Chemistry: Checking progress

   to distinguish between elements and other materials

   that each element is made up of atoms of one kind

   Provide groups of pupils with a set of statements, eg

    neon has only one sort of atom

    there are more non-elements than elements

    an apple is an element

    very few elements are liquids at room temperature

    all gases are elements

    water is an element: it is made of hydrogen and oxygen atoms

    and ask them to agree whether they are true or false.

   Discuss pupils’ answers with them and agree a list of key points about atoms and elements. Provide pupils with their own copy of the periodic table on which they can mark particular things, eg metals/non-metals.

  classify materials as elements and non-elements

  explain their classification

  identify that elements are made from atoms of one kind

  make some generalisations about elements

   Periodic tables used in other countries can be used to show pupils that the symbols for the elements are the same. These may be found on the internet.

   KS3 Chemistry:  How do we get all the other materials?

   that new materials are formed when atoms join together in different ways

   that compounds are formed when atoms combine

   that atoms can combine to form molecules

   Remind pupils of all the materials they mentioned in the first activity and ask them to suggest how these might be made from the limited number of atoms of different kinds. Remind them of the earlier activity using bricks as models and of some of the ‘materials’ that were made from bricks of different kinds.

   Establish the idea that when these materials are made the atoms combine or join. Introduce the terms ‘molecule’ and ‘compound’, show models or photographs of models, of simple and more complicated molecules, to illustrate the point. If possible also provide samples of the compounds and their formulae.

  explain the existence of compounds in terms of atoms joining together

  describe compounds, eg water is made of hydrogen and oxygen joined together

  describe some simple molecules, eg carbon dioxide is made of one carbon atom joined to two oxygen atoms

   It may be helpful if pupils make their own models of some simple molecules and relate these to their chemical formulae.

   Some teachers may want to include models of giant ionic/covalent structures. It is not necessary at this stage to explain the difference, although it is important to avoid talking about a molecule of sodium chloride, for example.

   Extension: pupils could find out about ‘new’ compounds (there are about 5000 registered each day).

    KS3 Chemistry: How can we represent the changes when new materials are made?

   that atoms of elements combine to form molecules of compounds

   that in chemical changes new substances are formed

   to represent and explain chemical reactions by word   equations, models or diagrams

   Show pupils some reactions between elements, eg

    hydrogen and oxygen

    sodium and chlorine

    carbon and oxygen

    copper and sulphur

    and ask them to record their observations in terms of the appearance of the reactants and the products and to represent the reactions by word equations, simulation software, models or diagrams, making clear that when the compound is formed the atoms join. Help pupils to represent the compounds formed by formulae and models. Ask pupils to explain individual reactions in these terms and to question others about their representations.

   Extend by showing that water can be split into hydrogen and oxygen by electrolysis.

  describe what happens in some chemical reactions and name the product

  explain compound formation in terms of atoms joining, eg using equations, diagrams, models

  show understanding of compound formation in asking questions about others’ representations of chemical reactions

   Pupils will have seen the burning of some elements in oxygen in unit 7F ‘Simple chemical reactions’, where they first encountered word equations.

Safety

eye protection and safety screens should be used. Ensure pupils are at a safe distance. Sodium is corrosive and highly flammable, chlorine is toxic and irritant. Some of these reactions are violent. With copper and sulphur there is a risk of producing toxic and irritant sulphur dioxide

hydrogen and oxygen: don’t explode more than 300cm3 hydrogen indoors. Hearing protectors are needed if a large volume is exploded outside

sodium and chlorine: place dry sand (50p size) on a heatproof mat. Place a piece of cleaned-up sodium on a crucible lid, ignite, quickly invert a gas jar of chlorine over it

copper and sulphur: use about 3g copper and 1.5g powdered roll sulphur in a borosilicate boiling tube. Insert a plug of mineral wool in the top. Heat until the reaction starts

     KS3 Chemistry: How can we represent the changes when new materials are made? (Cont.)

   to predict what might be formed from a chemical reaction between elements

   to heat metals in air safely

   Invite pupils to investigate one or more simple reactions first hand, eg what happens when magnesium ribbon is heated strongly in air. Encourage pupils to predict what the product might be on the basis of their prior work. Suggest that they identify and evaluate the product by comparing its appearance and behaviour with that of a known sample of magnesium oxide. Similar experiments could be carried out with zinc and copper to form their oxides.

   Ask pupils to represent the reactions as in the previous activity and to predict what might be formed in other reactions.

  predict the product of some simple reactions, eg zinc oxide from zinc and oxygen, iron sulphide from iron and sulphur

  interpret the names and/or formulae of binary compounds in terms of the elements of which they are composed

  make a sample of an oxide safely

   Teachers may need to explain that it is not true that all chemical reactions involve elements as reactants and compounds as products. Pupils will consider reactions between compounds in later units.

   Pupils will need time to practise using the chemical names of compounds, eg making the change from oxygen to oxide.

   It is helpful for pupils to become familiar with formulae for common compounds and to relate these to models showing the numbers of atoms. Teachers will be able to judge how far to take explanations of differences in formulae with different pupils.

   Extension: list for some pupils the formulae of the products of the reactions seen and introduce the idea of ‘combining power’ using a simple model, eg card cut-outs of elements, ball-and-spoke models. Ask pupils to use the models to predict the formulae of other metallic oxides, chlorides and sulphides. It is helpful to be explicit that the models are not representations of real atoms.

Safety  

when magnesium is heated, eye protection should be used and the burning metal should not be looked at directly

KS3 Chemistry: Reviewing work

   to distinguish between elements and non-elements

   to identify the scientific knowledge relevant to a particular question

   to make sure they are working safely

   to explain how their work provides evidence about a question

   to discuss and question what they are learning and how it is relevant when using different variables

   Give pupils sets of statements, eg

    made of only one sort of atom

    symbol C

    formula KF

    made of different atoms joined together

    made of atoms

    gives off carbon dioxide when it is heated

    a solution of salt in water

    and ask them to decide whether or not an element is described or whether it is not possible to tell.

    Extend for some pupils with more challenging statements, eg

    formula CO

    symbol Co

    formula O2

    breaks into two new materials when it is heated

   Explain that they are going to test their understanding in a practical activity and provide them with a sample of an ‘unknown’ material (copper carbonate) and challenge them to find evidence (practical or from data) of whether it is an element. Where necessary, prompt pupils by referring back to the first part of the activity. Ensure that what pupils propose is safe and, where necessary, help them to carry out their plan. Ask pupils to record what they did, their results and to explain what their results show. Discuss pupils’ results with them and invite them to ask each other questions about what they did and what it showed. Bring together evidence from all investigations.

   Help pupils to summarise the reactions of copper carbonate in a word equation, making clear which reactants and products are elements and which are compounds. Emphasise that the changes are chemical reactions in which new materials were made.

  identify statements describing elements and non-elements, explaining their decisions

  identify methods that will provide appropriate evidence, eg comparison of appearance with appearance of elements; change in mass on heating

  carry out their work safely

  explain how their results provided evidence, eg it changed colour and lost mass; if an element joins with something else it will gain mass

   Pupils may suggest a variety of things to do, eg searching a database of elements.

   Some pupils will need a good deal of help in planning what to do, but are likely to find it easier to explain what their results show.

   Extension: pupils could try to find out what causes the loss in mass. They are likely to have used the lime water test for carbon dioxide in unit 7F ‘Simple chemical reactions’. Some pupils could be challenged to think up alternative explanations for their evidence, eg it lost mass because it combined with oxygen and made carbon dioxide, which escaped, and how to decide between the explanations. It may be helpful with these pupils to introduce the symbol equation for the reaction.

Safety  

copper carbonate is harmful. One product (copper oxide) is an irritant. Eye protection should be used. Teachers will need to check pupils’ plans for health and safety, eg that appropriate quantities are to be used, before practi­cal work begins

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry - KS3 SCIENCE Unit 8F Compounds and mixtures


KS3 Chemistry In this unit you will learn to ..

  • distinguish between elements and compounds and how they are represented by symbols and formulae - these show the relative numbers and types of atom present
  • recognise chemical change as a process in which atoms join together in new ways
  • distinguish between compounds and mixtures
  • distinguish between chemical reactions in which new compounds are formed and the formation of mixtures
  • investigate temperature changes as liquids cool
  • use line graphs and choose appropriate scales for eg time, temperature or mass data.
  • distinguish between elements, compounds and mixtures in terms of the particles they contain
  • name and describe some common mixtures and use knowledge about separation techniques to suggest how they might be separated
  • identify melting and boiling points as the fixed temperatures at which elements and compounds change state and use the particle model to explain changes of state
  • know mixtures do not change state at fixed temperatures

Its handy if you ...

  • can name some elements
  • know that there are approximately 100 elements which are the building blocks for all materials
  • know that elements are composed of tiny particles called atoms
  • know that compounds are formed when atoms of different elements join
  • have explored a number of chemical reactions
  • have made and separated mixtures

Some important words for you to understand, use and spell correctly

  • words with precise scientific meaning, eg element, compound, mixture, atom, composition, pure
  • names of compounds, eg sodium carbonate, calcium chloride, hydrochloric acid

How are elements and compounds different?

  • that elements contain only one kind of atom
  • that compounds contain more than one kind of atom chemically bonded (joined) together
  • that formulae indicate the (relative) numbers of atoms in a compound
  • distinguish between elements and compounds in terms of names and symbolic formulae

How do compounds differ from the elements from which they are made?

  • that compounds contain elements that are chemically combined
  • that the properties of a compound are different from those of the elements from which it is made
  • that a compound always contains the same elements in fixed proportions and relate this to interpreting formulae for compounds in terms of the relative numbers of atoms of different elements
  • effect of heating a mixture of iron and sulphur powders in ignition tubes - a red glow and no yellow powder left after their tube has cooled - what evidence for suggesting chemical change - to extract the contents - does it still contains a mixture or if a new chemical (compound) has been made?  write a word, picture or symbol equations for the reaction
  • show that the compound iron sulphide behaves differently from its constituent elements sulphur and iron, eg by adding a small amount of dilute acid to both and observing the differences in the way the mixture behaves compared to the compound.
  • names of compounds eg water, carbon dioxide, copper carbonate - compare the compounds with the elements from which they are made - describe differences between compounds and the elements from which they are made
  • consider the formulae of some of the oxides made in unit 8E ‘Atoms and elements’, eg magnesium, sodium and aluminium oxides, and the fact that compounds are made from elements in fixed proportions - pictures showing particles in examples of elements, compounds and various mixtures of elements and/or compounds

Do compounds react chemically?

  • that compounds can react chemically
  • observe a number of test tube chemical reactions in which visible changes occur, eg mixing sodium carbonate solution and iron(II) chloride solution; adding dilute hydrochloric acid to solid magnesium carbonate; adding dilute ammonia solution to copper sulphate solution; heating sucrose
  • identify appropriate indications of chemical reactions
  • state that chemical reactions took place between the compounds
  • note that some physical changes also involve colour changes and gas evolution, and that a chemical reaction is distinguished by changes in the ways the atoms are bonded together.

Are there other sorts of material besides elements and compounds?

  • reminder about differences between compounds and mixtures eg in unit 7H ‘Solutions’ and show them examples of mixtures they may have encountered, eg iron and sulphur, chalk in water, seawater, air, soil, rocks, ink, shaving foam
  • and drawing diagrams to illustrate the particles in elements and compounds and extending this to mixtures
  • criteria for deciding whether something is a mixture or not
  • the idea that compounds can be represented by a formula whereas mixtures vary in composition and have no fixed formula, eg by showing samples of compounds together with molecule models, and contrasting these with samples of mineral water which is a mixture
  • the meaning of ‘pure’ when applied to a material, eg What is ‘pure’ orange juice? What is ‘pure’ water?
  • what is meant by ‘pure’ and ‘impure’ and link to eg the illustrations of elements, compounds and mixtures made earlier in the activity
  • name some everyday mixtures, eg air (gases), seawater and mineral water (which are both liquid water containing dissolved gases and solids)
  • identify that mixtures (eg above) can vary in composition and can be separated (eg in unit 7H ‘Solutions’)
  • the idea of rocks as mixtures is explored more fully in unit 8G ‘Rocks and weathering’ and unit 8H ‘The rock cycle’ but handy to use the same rock samples in this activity
  • name the main gases present in air and give approximate proportions of these (the particles maybe element atoms, element molecules and compound molecules)
  • explain clearly how air can be separated into its components - if cooled enough under pressure it will liquefy
  • describe clearly some uses of the components of air
  • related work on photosynthesis and respiration in unit 8B ‘Respiration’, unit 9B ‘Fit and healthy’ and unit 9C ‘Plants and photosynthesis’, and air pollution in unit 9G ‘Environmental chemistry’.
  • that elements and compounds melt and boil at particular temperatures and the temperatures are characteristic of these substances (note boiling point is always above the melting point!)
  • that mixtures do not melt or boil at fixed temperatures
  • look back at work on elements in unit 8E ‘Atoms and elements’ and to identify boiling points and melting points of some of these elements - note very high temperatures at which some metals melt
  • demonstration of the differences in the boiling point of tap water and salt solution which illustrates that mixtures do not have fixed melting or boiling points and they are different than the values for pure substances
  • describe how the melting point or boiling point of a mixture varies with composition
  • a temperature line was constructed in unit 8I ‘Heating and cooling’ - can investigate how temperature changes as they cool (surrounded by an ice/salt mixture) liquids eg pure and impure stearic acid.

KS3 Chemistry About the unit

In this unit pupils:

  distinguish between elements and compounds and how they are represented by symbols and formulae

  recognise chemical change as a process in which atoms join together in new ways

  distinguish between compounds and mixtures

  distinguish between chemical reactions in which new compounds are formed and the formation of mixtures

In scientific enquiry pupils:

  decide how many measurements are needed for reliable results

  present data as graphs

  interpret and draw conclusions from observations and graphs

  investigate temperature changes as liquids cool

KS3 Chemistry Where the unit fits in

This unit builds on unit 8E ‘Atoms and elements’.

Work on temperature, melting points and boiling points relates to unit 8I ‘Heating and cooling’.

This unit relates closely to unit 7G ‘Particle model of solids, liquids and gases’ and to
unit 7H ‘Solutions’. However, if teachers wish to introduce the idea of particles through unit 8E ‘Atoms and elements’, this unit could be taught before unit 7G ‘Particle model of solids, liquids and gases’ and unit 7H ‘Solutions’.

Ideas in this unit about mixtures are picked up in unit 8G ‘Rocks and weathering’ and
unit 8H ‘The rock cycle’.

Consideration of air as a mixture relates to unit 8B ‘Respiration’ and unit 9B ‘Fit and healthy’.

This unit, together with unit 8E ‘Atoms and elements’, provides the foundation for unit 9E ‘Reactions of metals and metal compounds’, unit 9F ‘Patterns of reactivity’, unit 9G ‘Environmental chemistry’ and unit 9H ‘Using chemistry’.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: make observations and measurements of mass and temperature; present results as line graphs and interpret these using scientific knowledge and understanding

some pupils will not have made so much progress and will: make observations and measurements of mass and temperature and, with help, present these as line graphs

some pupils will have progressed further and will: explain how scales they chose for graphs enabled them to present results effectively; make suggestions of additional work to test conclusions of their investigations

in terms of materials and their properties

most pupils will: distinguish between elements, compounds and mixtures in terms of the particles they contain; name and describe some common mixtures and use knowledge about separation techniques to suggest how they might be separated; identify melting and boiling points as the fixed temperatures at which elements and compounds change state, and use the particle model to explain changes of state

some pupils will not have made so much progress and will: name some common elements, compounds and mixtures and distinguish between representations or models of these; describe how some mixtures could be separated and recognise changes of state in elements and compounds

some pupils will have progressed further and will: explain their criteria for classifying materials as elements, compounds or mixtures; represent some compounds by formulae and explain what these show about the numbers and types of atom present; describe how mixtures do not change state at fixed temperatures

KS3 Chemistry Prior learning

It is helpful if pupils:

  can name some elements

  know that there are approximately 100 elements which are the building blocks for all materials

  know that elements are composed of tiny particles called atoms

  know that compounds are formed when atoms of different elements join

  have explored a number of chemical reactions

  have made and separated mixtures

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  carry out a number of chemical reactions

  plan and carry out their own investigation of temperature changes

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide.  Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words with precise scientific meaning, eg element, compound, mixture, atom, composition, pure

  names of compounds, eg sodium carbonate, calcium chloride, hydrochloric acid

Through the activities pupils could:

  organise facts/ideas/information in an appropriate sequence

  group sentences into paragraphs which have a clear focus

  link ideas and paragraphs into continuous text that is organised and coherent

KS3 Chemistry Resources

Resources include:

  cards showing the symbols of elements and compounds and corresponding descriptions

  labels from bottles of mineral water, showing composition

  samples of rocks that are mixtures

  samples of everyday materials that are mixtures, eg milk powder, cola

  sources of information, eg video clips, about the composition of air and the uses of its constituents, eg British Oxygen leaflets

  database software and other data sources showing melting points and boiling points of elements and compounds

  temperature sensor and software

  simulation software illustrating particles present in elements, compounds and mixtures

Out-of-school learning

Pupils could:

  look at labels on household materials and on clothes to find out what they are made from and to identify the names of chemical compounds

    KS3 Chemistry: How are elements and compounds different?

   that elements contain only one kind of atom

   that compounds contain more than one kind of atom joined together

   that formulae indicate the (relative) numbers of atoms in a compound

   Review and extend pupils’ understanding of the difference between elements and compounds or non-elements by providing them with a series of cards, the first giving a description of appearance, the second the formula and the third the composition, eg one atom of oxygen joined to two atoms of hydrogen, and asking pupils in groups to match them in sets of three and to sort into elements and non-elements.

   Make sure that pupils are clear that compounds contain atoms of more than one kind joined together.

  distinguish between elements and compounds

  relate formulae to the numbers and types of atom in a compound 

   If unit 8E ‘Atoms and elements’ and unit 8F ‘Compounds and mixtures’ are taught in a block, pupils may need to spend less time on these introductory activities. If they are not, teachers may need to provide a context in which ideas can be revisited.

   If ionic compounds are included, it is sufficient to treat the formula as a ratio, eg one atom of magnesium to one of oxygen in magnesium oxide. It is important not to imply that ionic compounds consist of molecules.

    KS3 Chemistry: How do compounds differ from the elements from which they are made?

   that compounds contain elements that are chemically combined

   that the properties of a compound are different from those of the elements from which it is made

   that a compound always contains the same elements in fixed proportions

   Demonstrate making or invite pupils to make a mixture from two elements: sulphur (powder) and iron (powder). Ask pupils to heat a mixture of iron and sulphur in ignition tubes until they observe a red glow and, after their tube has cooled, to extract the contents and try to find out if it still contains a mixture or if a new chemical (compound) has been made. Through discussion of their results, establish that they have made a compound. Help pupils to write picture and word equations for the reaction.

   Demonstrate that the compound iron sulphide behaves differently from its constituent elements sulphur and iron, eg by adding a small amount of dilute acid to both and observing the differences in the way the mixture behaves compared to the compound.

   Ask pupils for names of compounds they have used, eg water, carbon dioxide, copper carbonate; provide them with samples and ask them to compare the compounds with the elements from which they are made. Establish, through discussion of the formulae of some of the oxides made in unit 8E ‘Atoms and elements’, eg magnesium, sodium and aluminium oxides, that compounds are made from elements in fixed proportions. Provide pupils with drawings or software simulations showing particles in examples of elements, compounds and various mixtures of elements and/or compounds. Ask them to identify the types of particles present and what the drawings represent in terms of elements, compounds and mixtures.

  describe differences between compounds and the elements from which they are made

  interpret formulae for compounds in terms of the relative numbers of atoms of different elements

   Teachers may wish to draw pupils’ attention to the red glow continuing after heat has been removed as evidence of an energy change as the chemical reaction takes place.

   Extension: some pupils could try to make their own drawings starting from formulae or descriptions of composition.

Safety

eye protection should be worn throughout. A 7:4 iron:sulphur mixture by mass should be used. The mixture can be heated in a small test tube with a mineral wood plug in its mouth. In the course of this activity, toxic and corrosive sulphur dioxide may be produced if the sulphur catches fire

– when testing the product with dilute acid, eye protection should be worn and very small quantities used as hydrogen sulphide (toxic) and hydrogen (explosive) may be formed

   KS3 Chemistry:  Do compounds react chemically?

   to carry out test tube reactions

   to identify observations relevant to a piece of work and draw conclusions from these

   that compounds can react chemically

   to organise ideas into an appropriate sequence 

   Ask pupils to carry out a number of test tube chemical reactions in which visible changes occur, eg

    mixing sodium carbonate solution and iron (II) chloride solution

    adding dilute hydrochloric acid to solid magnesium carbonate 

    adding dilute ammonia solution to copper sulphate solution

    heating sucrose

   Ask pupils to record their observations carefully, telling them that they are looking for evidence that chemical reactions making new materials have taken place. Ask pupils, in groups, to agree on a short paragraph about the reactions setting out the observations and evidence, then to exchange work and decide whether they agree or disagree with the evidence suggested, explaining their reasons.

  identify appropriate indications of chemical reactions

  state that chemical reactions took place between the compounds

  summarise what they observed and explain what this showed

   Pupils are likely to have explored chemical reactions in unit 7E ‘Acids and alkalis’ and unit 7F ‘Simple chemical reactions’. This activity could be extended by asking pupils to think again about the evidence for a chemical reaction in the reactions explored in those units. Teachers may need to emphasise that some physical changes also involve colour changes and gas evolution, and that a chemical reaction is distinguished by changes in the ways the atoms are bonded together.

Safety  

0.4 mol dm-3 solutions should be used. At this concentration, the sub­stances named are low hazard, but eye protection should be worn

    KS3 Chemistry: Checking progress

   to make connections between key ideas about chemical change 

   Ask pupils to produce a concept map related to chemical change using terms, eg atom, element, compound, burning, oxygen, formula, symbol, chemical, reaction, copper, oxide. Discuss pupils’ maps with them and if necessary help them to make an exemplar map to refer to in later work.

  link ideas in an appropriate way

  recognise additional links when these are pointed out 

   This activity and the next one are likely to show that pupils have a number of misconceptions. Some of these may be tackled by discussing pupils’ ideas with them as they produce their concept map. Later activities in this unit, and activities in unit 9E ‘Reactions of metals and metal compounds’, unit 9F ‘Patterns of reactivity’ and unit 9H ‘Using chemistry’, provide further opportunities to revisit ideas about elements, compounds and chemical change.

    KS3 Chemistry: Are there other sorts of material besides elements and compounds?

   about differences between compounds and mixtures

   Remind pupils of work about mixtures in unit 7H ‘Solutions’ and show them examples of mixtures they may have encountered, eg iron and sulphur, chalk in water, seawater, air, soil, rocks, ink, shaving foam. Elicit what they understand by the term ‘mixture’, eg by asking them to draw diagrams to illustrate the particles in elements and compounds and extending this to mixtures, and establish their criteria for deciding whether something is a mixture or not. Introduce the idea that compounds can be represented by a formula whereas mixtures vary in composition, eg by showing samples of compounds together with molecule models, and contrasting these with samples of mineral water together with labels from bottles showing that the water is a mixture.

   Ask pupils for their ideas of the meaning of ‘pure’ when applied to a material, eg What is ‘pure’ orange juice? What is ‘pure’ water? Establish what is meant by ‘pure’ and ‘impure’ and link back to the illustrations of elements, compounds and mixtures made earlier in the activity. Reinforce using simulation software illustrating elements, compounds and mixtures.

  name some everyday mixtures, eg air, seawater, mineral water

  identify that mixtures can vary in composition 

   Pupils will have had opportunities to make and separate some mixtures in unit 7H ‘Solutions’.

   The idea of rocks as mixtures is explored more fully in unit 8G ‘Rocks and weathering’ and unit 8H ‘The rock cycle’. It would be helpful to use the same rock samples in this activity.

   that air is a mixture of gases

   that air can be separated into its constituents

   to group sentences into paragraphs which have a clear focus

   to link ideas and paragraphs into continuous text

   Ask pupils how a mixture of a solid and liquid, eg blue ink, or of coloured dyes, eg inks in a felt-tip pen can be separated. Use secondary sources,
eg video clips, to illustrate that air is a mixture and ask them why it might be important to separate the gases in air. Provide pupils with appropriate information about the separation of air into its components and the uses of these. Extend the work, as appropriate, by asking them to find out differences between inhaled and exhaled air, the importance of ventilation in rooms, how the composition of air dissolved in water varies and about the composition of air in passenger planes. Ask pupils to produce an information leaflet about air reminding them about the importance of organising facts, ideas and information into sentences, which are then grouped into paragraphs with appropriate linkages.

  name the main gases present in air and give approximate proportions of these

  explain clearly how air can be separated into its components

  describe clearly some uses of the components of air

  sequence and organise ideas into coherent, continuous text

   It may be helpful to use this activity with some pupils to reinforce the idea that some of the gases in air consist of single atoms, while others are molecules.

   This relates to work on photosynthesis and respiration in unit 8B ‘Respiration’, unit 9B ‘Fit and healthy’ and unit 9C ‘Plants and photosynthesis’, and to
work on air pollution in unit 9G ‘Environmental chemistry’.

   This activity provides an opportunity to use ICT for producing the leaflet.

    KS3 Chemistry: Are there other sorts of material besides elements and compounds? (Cont.)

   that elements and compounds melt and boil at particular temperatures

   that mixtures do not melt or boil at fixed temperatures

   to use data from secondary sources 

   Ask pupils to look back at the work they did on elements in unit 8E ‘Atoms and elements’ and to identify boiling points and melting points of some of these elements. Illustrate with video clips the very high temperatures at which some metals melt. Establish, through discussion of their data and other data from secondary sources, that changes of state of pure elements and compounds occur at a fixed temperature and that the temperature is a characteristic of the material that is changing state.

   Give pupils examples of melting points and boiling points. Ask them whether boiling point is always higher than melting point and help them to use database software to test their predictions. Establish through discussion that melting and freezing are opposites and occur at the same temperature for a given material. Illustrate with video clips that gases can be cooled enough to liquefy and may eventually solidify. Relate this back to work on separation of air.

   Ask pupils if they can find in any data book or database the boiling point of air and to explain why they cannot. Carry out a quick demonstration of the differences in the boiling point of tap water and salt solution and introduce the idea that mixtures do not have fixed melting or boiling points.

  identify the melting and boiling points of a range of elements and compounds

  explain that these are characteristic of the element or compound

  describe how the melting point or boiling point of a mixture varies with composition

   Pupils will have constructed a temperature line in unit 8I ‘Heating and cooling’. They could add some of the melting points and boiling points considered in this activity. At this stage it is not necessary to consider variation of boiling point with atmospheric pressure unless pupils raise the question.

   If it is possible to obtain a sample of liquid nitrogen, demonstration of its properties provides additional interest and challenges pupils’ thinking.

Safety  

ensure liquid nitrogen is transported safely in a properly sealed Dewar flask. Beware cold burns. Obtain a special risk assessment

   to decide how many measurements to make

   to relate results to scientific knowledge and understanding

   to consider whether there was other evidence they could have collected

   Provide pupils with two liquids labelled A and B (distilled water and salt solution). Tell them that they are going to investigate how temperature changes as they cool (surrounded by an ice/salt mixture) and use this and any other sample tests to find out as much as possible about the liquid. Ask the pupils to plan what to do, including how frequently they will make measurements, and to produce an account of what they did, tables and graphs of results and to use all their results to draw conclusions about the liquids.

  identify differences between the graphs and explain that these show one is a pure liquid and the other is not

  suggest additional tests,
eg evaporating both liquids, finding the boiling point of both liquids, explaining what these might show

   Pupils are likely to need guidance on how to use the ice/salt mixture. A good supply of ice will be needed for class investigations.

   A temperature sensor attached to a computer could be used in this activity

   As an additional or alternative activity, some pupils could investigate the cooling of pure and impure stearic acid.

   In unit 8I ‘Heating and cooling’, pupils investigate temperature changes as ice and salol melt and freeze. They could be reminded of this work.

Safety  

– teachers will need to check pupils’ plans for health and safety before practical work begins

    KS3 Chemistry: Reviewing work

   about key differences between elements, mixtures and compounds 

   Give pupils a list of statements, eg

    is made up of atoms 

    has a definite composition

    is a result of atoms joining together 

    contains different substances which are not chemically combined

    can be represented by a chemical formula 

    Ask them to assign each to one or more of element, compound and mixture.

   Some pupils will also be able to sort the statements in each category so that similar ones are grouped together. Check those that apply to two or to all three, eg contains molecules, and those which are ‘difficult’, and agree a summary sheet consisting of correctly allocated statements. Ask them to add familiar examples of elements, compounds and mixtures to their summary sheet.

  identify characteristics of elements, compounds and mixtures, explaining the basis for their decisions

   Extension: for some pupils more complex statements could be used, eg contains some substances with a definite composition.

   This activity extends the first part of the ‘reviewing work’ activity at the end of unit 8E ‘Atoms and elements’. It may be helpful to use the same statements, together with additional ones, and ask pupils whether they feel more confident in assigning the statements.

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry - KS3 SCIENCE Unit 8G Rocks and weathering


KS3 Chemistry In this unit you will ...

  • learn about rock texture as one of the key characteristics of different rock types
  • model rock texture
  • learn about the processes of weathering, erosion, transportation and sedimentation
  • relate processes, eg evaporation and dissolving, involved in rock formation to processes observed in other contexts
  • consider processes operating on different timescales
  • consider how evidence from sedimentary layers and from fossils has led to changes in ideas about the development of the Earth
  • describe evidence for a sequence of geological events; suggest a question to be investigated about the movement of sediment
  • use evidence from several sources to describe a sequence of geological events
  • describe rock specimens in terms of texture and relate this to properties such as porosity
  • describe the physical and chemical processes by which rocks are weathered and transported and relate these to features of the environment
  • describe and explain the processes by which layers of sediments are produced
  • relate processes of chemical weathering to the reactions of particular grains with acids; relate sedimentary layers to the processes by which they were produced

Its handy if you ..

  • know that there are rocks under the surface of the Earth and that soils come from rocks
  • can name some examples and uses of rocks
  • know that solids, liquids and gases are made of particles and about differences between the way particles are arranged in solids and liquids
  • have experience of determining the pH of a solution and relating this to acidity or alkalinity
  • know that dissolved solids are left behind when water evaporates

Some important words for you to understand, use and spell correctly

  • words and phrases for physical processes associated with rock formation, eg chemical weathering, abrasion, sedimentation
  • words and phrases for timescales over which change occurs, eg millions of years, millennia
  • names for specific rocks, eg granite, limestone, sandstone
  • words and phrases relating to geological features, eg sedimentary layers, porosity
  • words and phrases relating to scientific enquiry, eg time-lapse photography, sequence of events

What are rocks made of?

  • that rocks are usually made up of a mixture of mineral grains
  • that two main textures can be recognised
  • how to use experimental evidence and models to explain the texture of different rocks
  • given samples of rocks to sort them into groups, explain the basis for their groups eg texture or colour ?
  • looking at samples of granite and sandstone - explain why one rock produces bubbles in water and the other does not - investigate the absorption of water by weighing samples before and after immersion to illustrate porosity
  • the idea that rocks are almost always mixtures of materials containing different grains which fit together
  • explain that some grain shapes are interlocking and some are not, eg some grains fit together and others do not; when the grains don’t fit there are spaces and the water goes into these
  • relate evidence about porosity to the way in which grains fit together

How does rain cause rocks to weather?

  • that rocks at the Earth’s surface disintegrate through exposure to water in the environment, which causes chemical reactions
  • to use knowledge and understanding of the composition of igneous rocks to explain results of changes over time
  • observe rock materials out of doors, eg in a cemetery or on a high street, or show them pictures, video clips of rocks/building materials in the locality of the school ad note changes that have occurred over time
  • compare older surfaces with new or chipped surfaces to record evidence of discoloration and/or crumbling. Ask them to speculate about possible causes. Note the effects of weathering under trees or adjacent to soil and suggest reasons for this.
  • reminder about earlier work on acids and alkalis and show that samples of rainwater are slightly acidic, and identify acidic rain as a cause of chemical weathering
  • compare fresh granite with weathered granite to observe any changes to minerals
  • simulate wet, oxygen-rich, acidic conditions using dilute hydrochloric acid and hydrogen peroxide in a 50:50 mixture, effect on sample of granite in the solution, describe and explain the changes
  • describe changes in rocks and building materials over time
  • describe changes in granite exposed to acid and relate these to changes in particular grains that are dissolved by acids

How do changes in temperature cause rocks to weather?

  • that rocks are broken down by forces that result from stresses generated when water in cracks and fissures expands on freezing, explain how water absorbed by rocks expands on freezing and fragments the rock
  • that rocks at the Earth’s surface are broken down by forces that result from stresses generated when rocks expand and contract on heating and cooling
  • the magnitude of the forces arising from expansion or contraction of a solid, eg by repeatedly heating a corner of a chip of granite to red heat then quenching it in cold water or by using a breaking-bar experiment, these forces are large enough to cause pieces of rock to break off and are most significant where there are large temperature ranges.
  • describe how changes in temperature can result in rock fragmentation
  • describe conditions when fragmentation is likely to occur
  • explain that the forces arising from expansion and contraction are great enough to break off pieces of rock
  • relate expansion and contraction to the particle model of matter

What happens to weathered pieces of rock?

  • that rock fragments become sediment grains which can be transported by water currents and deposited when the energy is dissipated and make predictions about where sediment is deposited
  • describe and record where water is moving quickly, and where it is moving slowly, and to use the results to predict where large and small fragments will be deposited.
  • use the results of their investigation to predict where different sizes of sediment might be moved or deposited in a river flowing into a lake or sea
  • that larger grains are not taken as far, as it requires more energy to move them
  • that sediment grains of similar size are deposited together
  • that as transportation times and distances increase, sediment grains become smaller and more rounded and are also sorted into similar sizes
Why do sediments form layers?
  • explain how sedimentary layers are the result of distinct episodes of sedimentation over a variety of timescales, so building up a sequence of events ...
  • how quickly sediment settles into layers using grains of different sizes, eg clay, sand, gravel, in a jar of water, observe if the layers have sharp boundaries or grade into each other and to relate this to the conditions under which the layers were formed, what controls the thickness of layers? effect of particle size?
  • sharp boundaries are formed when there is a time interval between the deposition of the layers.
  • sedimentary layers can be formed by the evaporation of waters containing dissolved salts
  • that the remains of dead organisms and their shelly material can accumulate to form sediments
  • to use evidence in rock layers to suggest a sequence of events over time
  • about the use of fossils as evidence
  • how a sequence of sediments can be built up by covering the residue from evaporated sea water with a layer of clay and shells to represent the remains of dead organisms, adding more seawater and allowing it to evaporate. Extend to the formation of oil, eg by using video clips.
  • diagram showing different strata and ask them to tell the story of how the layers were formed and why fossils are often found in sedimentary layers.
  • find out about how evidence in rock strata, eg fossils, coal layers, has been used to develop other ideas about changes in the Earth over time, eg continental drift, climate changes.

KS3 Chemistry About the unit

In this unit pupils:

  learn about rock texture as one of the key characteristics of different rock types

  model rock texture

  learn about the processes of weathering, erosion, transportation and sedimentation

  relate processes, eg evaporation and dissolving, involved in rock formation to processes observed in other contexts

  consider processes operating on different timescales

In scientific enquiry pupils:

  consider how evidence from sedimentary layers and from fossils has led to changes in ideas about the development of the Earth

  frame questions to be investigated

  make qualitative observations, including using time-lapse photography to record gradual changes, evaluating methods used

  present data in an appropriate way

  use scientific knowledge and understanding to explain observations

  investigate a question about sedimentation

KS3 Chemistry Where the unit fits in

This unit builds on unit 3D ‘Rocks and soils’ in the key stage 2 scheme of work.

The two units about Earth science draw on work about pH in unit 7E ‘Acids and alkalis’, work on evaporation in unit 7H ‘Solutions’, work on mixtures in unit 8F ‘Compounds and mixtures’ and work on changes of state in unit 8I ‘Heating and cooling’.

This unit relates to unit 2 ‘The restless earth – earthquakes and volcanoes’, unit 7 ‘Rivers – a fieldwork approach’ and unit 8 ‘Coastal environments’ in the geography scheme of work.

The unit provides a foundation for work on the rock cycle in unit 8H ‘The rock cycle’. Ideas about weathering are revisited in unit 9G ‘Environmental chemistry’. Together with unit 8H ‘The rock cycle’, this unit lays the foundation for work in key stage 4 on rock formation and deformation and on processes involving tectonic plates.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: describe evidence for a sequence of geological events; suggest a question to be investigated about the movement of sediment and, with help, identify an appropriate approach; use ICT to make and record observations and explain these using scientific knowledge and understanding

some pupils will not have made so much progress and will: describe changes in rocks or rock fragments over time; with help, identify a question about movement of sediment to be investigated and use ICT to make and record observations related to the question

some pupils will have progressed further and will: use evidence from several sources to describe a sequence of geological events

in terms of materials and their properties

most pupils will: describe rock specimens in terms of texture and relate this to properties such as porosity; describe the physical and chemical processes by which rocks are weathered and transported and relate these to features of the environment; describe and explain the processes by which layers of sediments are produced

some pupils will not have made so much progress and will: describe rock specimens and recognise that different rocks have different textures; describe some effects of weathering and recognise sedimentary layers

some pupils will have progressed further and will: relate processes of chemical weathering to the reactions of particular grains with acids; relate sedimentary layers to the processes by which they were produced

KS3 Chemistry Prior learning

It is helpful if pupils:

  know that there are rocks under the surface of the Earth and that soils come from rocks

  can name some examples and uses of rocks

  know that solids, liquids and gases are made of particles and about differences between the way particles are arranged in solids and liquids

  have experience of determining the pH of a solution and relating this to acidity or alkalinity

  know that dissolved solids are left behind when water evaporates

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  plan and carry out an investigation into sedimentation

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  words and phrases for physical processes associated with rock formation, eg chemical weathering, abrasion, sedimentation

  words and phrases for timescales over which change occurs, eg millions of years, millennia

  names for specific rocks, eg granite, limestone, sandstone

  words and phrases relating to geological features, eg sedimentary layers, porosity

  words and phrases relating to scientific enquiry, eg time-lapse photography, sequence of events

KS3 Chemistry Resources

Resources include:

  a collection of rocks, either one available commercially or one compiled by the department, eg conglomerate, sandstone, limestone, chalk, mudstone, shale, slate, marble, quartz, granite, gabbro, basalt, pumice, obsidian, some of which are typical of their type and some of which have unusual features

  access to pictures, CD-ROMs, internet sites showing geological landscapes and events, eg volcanic eruptions, both explosive and lava, and simulations of geological events which occur over many millennia

  examples of fossils or fossilised materials

  materials for modelling rivers

  digital camera for recording changes over a period of time

  secondary sources illustrating the work of Mary Anning

KS3 Chemistry Out-of-school learning

Pupils could:

  read books about the Earth and its history and newspaper articles about weather conditions (floods and high winds) or volcanic eruptions

  watch television programmes or videos about the Earth, which will help them understand how rocks are formed

  visit science museums to see displays about the Earth and its rocks as well as simulations which will help them to imagine the effects of earthquakes and the forces involved

  visit other museums and art galleries to see how rocks are used

  read science fiction texts about earlier geological ages

  visit the seashore to observe shingle, sand, river estuaries and cliffs, or  hills to observe peat and rock formations, eg limestone pavements

    KS3 Chemistry: What are rocks made of?

   that rocks are usually made up of a mixture of mineral grains

   that two main textures can be recognised

   how to use experimental evidence and models to explain the texture of different rocks

   Show pupils samples of rocks and ask them to sort them into groups. Ask them to explain the basis for their groups, prompting if necessary by asking questions, eg What makes the rock shiny? What can you see in the rock?
Is the rock all the same colour?
Ask pupils to record key responses. Discuss with them the words/observations that occurred most frequently.

   Provide pupils with samples of granite and sandstone and ask them to explore their textures, eg by close observation using a magnifier and by immersion in water. Ask pupils to explain why one rock produces bubbles in water and the other does not. Investigate the absorption of water by weighing samples before and after immersion to illustrate porosity. Model interlocking and non-interlocking textures, eg using a three-dimensional block puzzle and marbles, and relate observations to interlocking and non-interlocking textures. Ask pupils to record and explain their findings using annotated drawings and diagrams. Establish the idea that rocks are almost always mixtures of materials.

  describe rocks as containing different grains which fit together

  explain that some grain shapes are interlocking and some are not, eg some grains fit together and others do not; when the grains don’t fit there are spaces and the water goes into these

  relate evidence about porosity to the way in which grains fit together

   Rocks need to be chosen so that pupils will see easily that they are a mixture of different grains. The word most commonly used in their explanations/ descriptions may be ‘bits’.

   Some pupils may not realise that the term ‘rock’ as used by geologists includes unconsolidated material, such as sand, clay and peat, as well as harder materials.

   Differences between mixtures and chemical compounds are considered in unit 8F ‘Compounds and mixtures’.

   It may be helpful to illustrate porosity using sponges of different kinds.

    How does rain cause rocks to weather?

   that rocks at the Earth’s surface disintegrate through exposure to water in the environment, which causes chemical reactions

   how to record results over a period of time

   to use knowledge and understanding of the composition of igneous rocks to explain results of changes over time

   Take pupils to observe rock materials out of doors, eg in a cemetery or on a high street, or show them pictures, video clips of rocks/building materials in the locality of the school.

   Ask pupils to compare older surfaces with new or chipped surfaces to record evidence of discoloration and/or crumbling. Ask them to speculate about possible causes. Note the effects of weathering under trees or adjacent to soil and ask pupils to suggest reasons for this.

   Remind pupils about earlier work on acids and alkalis and show that samples of rainwater are slightly acidic.

   Ask pupils to compare fresh granite with weathered granite to observe any changes to minerals. Simulate wet, oxygen-rich, acidic conditions using dilute hydrochloric acid and hydrogen peroxide in a 50:50 mixture. Place a sample of granite in the solution and capture the changes daily for up to two weeks using a digital camera to create a time-lapse sequence. Ask pupils to examine, describe and explain the changes using a computer-generated slide show. Discuss with them why this is an effective way of recording results.

  describe changes in rocks and building materials over time

  identify acidic rain as a cause of chemical weathering

  describe and evaluate the use of time-lapse photography to record gradual changes

  describe changes in granite exposed to acid and relate these to changes in particular grains that are dissolved by acids

   Weathering of rocks and the formation of sedimentary rocks are considered before the formation of igneous rocks, as these processes are likely to be more familiar to pupils.

   The formation of acid rain is covered in more detail in unit 9G ‘Environmental chemistry’.

   A set of photographs of weathered materials in other environments may be useful. See suitable internet sites, eg
www.geo.duke.edu/sched/geopages/geo41/wea.htm
www.geo.duke.edu/sched/geopages/geo41/wea2.htm
https://athena.wednet.edu/curric/land/ landform

   Extension: present pupils with a map showing rainfall and temperature and ask them to suggest regions where extensive weathering might occur.

Safety  

use acid solutions in concentrations less than 0.4 mol dm-3 as these are low hazard

    How do changes in temperature cause rocks to weather?

   that rocks are broken down by forces that result from stresses generated when water in cracks and fissures expands on freezing

   that rocks at the Earth’s surface are broken down by forces that result from stresses generated when rocks expand and contract on heating and cooling

   Show pupils pictures or a video clip as a stimulus and ask them to suggest why mountaineers climbing in high mountains, eg the Alps or Himalayas, start early in the morning and try to complete their climbing on mountain faces before midday.

   Demonstrate the magnitude of the forces arising from expansion or contraction of a solid, eg by repeatedly heating a corner of a chip of granite to red heat then quenching it in cold water or by using a breaking-bar experiment. Establish with pupils that these forces are large enough to cause pieces of rock to break off and are most significant where there are large temperature ranges.

   Present pupils with a rock sample containing cracks and soak in water. Explain that this is to be used to model what happens when water freezes and thaws. Ask them to suggest how this might be done and how to record the results. Use a digital camera to create a time-lapse sequence showing the number of freeze–thaw cycles on the rock sample and ask pupils to examine the changes, particularly the width of cracks and the shape and size of fragments, using a computer-generated slide show. Discuss how the angular fragments are formed. Ask pupils to re-evaluate their suggestions about mountaineers and explain why rockfalls can be a major hazard to climbing.

  explain how water absorbed by rocks expands on freezing and fragments the rock

  describe how changes in temperature can result in rock fragmentation

  describe conditions when fragmentation is likely to occur

  explain that the forces arising from expansion and contraction are great enough to break off pieces of rock

  relate expansion and contraction to the particle model of matter

   If pupils do not know that water expands when it freezes, a demonstration using a plastic bottle filled with water frozen in a freezer would be helpful.

   Extension: ask pupils to use a hand lens to look at a sample of highly porous rock that has been soaked in a saturated salt solution, eg sodium sulphate solution, and then dried, and to note the presence of crystals occupying the pore spaces. Discuss how the salt can be leached in solution from the rock and then crystallised on nearing the surface of the rock.

   Extension: use a digital camera to create a time-lapse sequence showing a number of saturation–drying cycles on the rock sample. Ask pupils to examine the changes using a computer-generated slide show and to record the size and shape of the fragments that are formed. Ask pupils to explain how the growth of salt crystals breaks down the rock.

Safety  

– eye protection should be worn when heating granite

    KS3 Chemistry: Checking progress

   to relate a landscape to a process of weathering

   Show pupils photographs of natural scree slopes, eg Wast Water in the Lake District, and ask them to suggest how rock ended up as fragments in a pile at the bottom of the cliff and what the scree slope tells us about past conditions. Ask pupils what characteristics would lead to rocks being weathered easily.

  identify conditions under which rocks fragment

  explain the formation of the scree slope in terms of these conditions

   Pupils would not be expected to recall terms such as ‘scree slope’.

   Extension: to test their ideas, pupils could investigate rock resistance by shaking several small specimens of different rock types in a plastic container and recording changes of size after different time intervals.

   KS3 Chemistry:  What happens to weathered pieces of rock?

   that rock fragments become sediment grains which can be transported by water currents and deposited when the energy is dissipated

   to make predictions about where sediment is deposited

   Review work on weathering and fragmentation of rocks. Find out pupils’ ideas about how rock fragments are transported and changed by asking them to sequence a set of statements/drawings and to explain their sequence. Help pupils to investigate water flow in a channel and its overflow by using square guttering that channels water into a large trough. Use a dye, eg ink, to track what happens to the current along the gutter and in the trough. Discuss the spreading out of the dye and ask pupils to describe and record where water is moving quickly, and where it is moving slowly, and to use the results to predict where large and small fragments will be deposited.

  state that rock fragments can be transported by flowing water

  use the results of their investigation to predict where different sizes of sediment might be moved or deposited in a river flowing into a lake or sea

   Pupils’ understanding of how different grains behave can be reinforced by adding a cupful of mixed-sized grains of sediment to a jar of water and swirling it around. Ask pupils to observe which grains roll, which bounce and which ‘fly’, eg in suspension.

Safety  

take care that floors do not become wet and slippery

   how to frame a question that can be investigated

   to decide whether evidence supports predictions

   that larger grains are not taken as far, as it requires more energy to move them

   that sediment grains of similar size are deposited together

   Ask pupils to suggest how water flow might affect the movement of different-sized grains of sediment and to plan how to investigate a specific question using gravel, sand and muddy soil. As part of their investigation, ask pupils to observe and record the distribution of sediment grain size along the gutter and to explain the relationship with volume and speed of water flowing. Bring together the outcomes of all investigations, asking pupils to describe what they did, what problems they encountered and how they overcame them.

  suggest a question that can be investigated, eg Is sand carried as far as gravel? Does the distance sand travels depend on the width of the channel?

  relate the outcomes of their investigation to the grain size and/or volume and speed of water

  conclude that grains of similar size are deposited together

Safety  

teachers will need to check pupils’ plans for health and safety before practical work begins

    KS3 Chemistry: What happens to weathered pieces of rock? (Cont.)

   that as transportation times and distances increase, sediment grains become more rounded and are also sorted into similar sizes

   to present data in an appropriate form

   Show pupils that the change in sediment shape and size during transportation can be simulated by shaking plaster cubes in a cylindrical container. Ask them to investigate what happens over several cycles of tumbling in terms of, eg number, average, mass or shape of fragments after each cycle. Ask pupils to show the results as line graphs or appropriate drawings, and to explain what has caused the changes and what happens to the ‘lost’ mass. Bring together the class results with the pupils, and help them to make generalisations about fragmentation.

  identify changes in fragments as time and distance of transportation increase, eg become smaller, smoother, rounder

  display their results, eg line graph for average mass of fragments, drawings for shape of fragments

 

    KS3 Chemistry: Checking progress

   about fragmentation and transportation

   Show pupils photographs, video clips of rivers full after a storm and in normal state and ask them a series of questions, eg

    Why does the river appear dirty?

    Where has the dirt come from?

    What happens when the water level drops?

    Why does the river become clearer?

   Help pupils to generate key points about transportation and formation of sediment grains from their responses and the responses of others.

  identify the source of ‘dirt’ in rivers in flood

  make generalisations about transport and formation of sediment grains, eg larger grains don’t get carried so far

 

   KS3 Chemistry:  Why do sediments form layers?

   that sedimentary layers are the result of distinct episodes of sedimentation over a variety of timescales

   to suggest explanations for observations they make

   Show pupils photographs or video clips of cliffs with sedimentary strata and ask them to suggest, eg in drawings or annotated diagrams, how the layers were formed.

   Ask pupils to investigate how quickly sediment settles using grains of different sizes, eg clay, sand, gravel, in a jar of water.

   Ask pupils to observe if the layers have sharp boundaries or grade into each other and to relate this to the conditions under which the layers were formed. Ask pupils to speculate about what controls the thickness of layers and to explain their ideas to others.

  describe how sediments settle to form layers

  identify in drawing or annotation that different layers were formed at different times

  relate observations about sedimentary layers to factors, eg particle size

   Sharp boundaries are formed when there is a time interval between the deposition of the layers.

    KS3 Chemistry: Why do sediments form layers? (Cont.)

   that sedimentary layers can be formed by the evaporation of waters containing dissolved salts

   that the remains of dead organisms and their shelly material can accumulate to form sediments

   to use evidence in rock layers to suggest a sequence of events over time

   about the use of fossils as evidence

   Ask pupils whether water in rivers, lakes, seas has solids dissolved in it. Remind them of earlier work on different types of water. Ask them to explain the origin of the salts. Use a flow diagram to explain how salts become concentrated in seas or lakes. Ask pupils to suggest what would happen if the seawater evaporated and how to test their ideas. Modify the flow diagram to discuss how seas and lakes can dry up.

   Explore with pupils how a sequence of sediments can be built up by covering the residue from evaporated sea water with a layer of clay and shells to represent the remains of dead organisms, adding more seawater and allowing it to evaporate. Extend to the formation of oil, eg by using video clips.

   Give pupils a simplified diagram showing different strata and ask them to tell the story of how the layers were formed and why fossils are often found in sedimentary layers.

   Extend by asking pupils to use secondary sources to find out about Mary Anning and the fossil specimens she collected.

  describe how dissolved solids are left behind when water evaporates

  describe a possible sequence of events leading to a pattern of sedimentary strata

  justify their sequence using the evidence from the layers

   Pupils are likely to have investigated different types of water at key stage 2 to find out whether they contain dissolved solids.

   The use of fossil fuels is included in unit 7I ‘Energy resources’.

   Extension: pupils could be asked to find out about how evidence in rock strata, eg fossils, coal layers, has been used to develop other ideas about changes in the Earth over time, eg continental drift, climate changes.

   Teachers will be aware of the need to be sensitive to different religious beliefs.

Safety  

care is needed if the seawa­ter is evaporated by heating. Eye protec­tion should be worn

    KS3 Chemistry: Reviewing work

   to relate key ideas about geological changes to each other

   Provide pupils with a series of photographs/diagrams/drawings and brief descriptions, eg a muddy river estuary – grains of mud and sand deposited at the edges of rivers; a pile of rocks at the bottom of a scree – water that gets into cracks and expands as it freezes, and ask them to match them. Where pupils have matched images and descriptions in different ways, ask them to justify their choices to each other.

  match a description of a geological process to an illustration of it

  relate the processes involved in weathering, transport and sedimentation

 

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry  KS3 SCIENCE Unit 8H The rock cycle


KS3 Chemistry In this unit you should ...

  • learn about the major rock-forming processes
  • learn how rock-forming processes are linked by the rock cycle
  • use the concept of rock texture as one of the key characteristics of igneous, sedimentary and metamorphic rocks
  • relate processes observed in other contexts, eg crystallisation, to processes involved in the rock cycle
  • consider processes operating on different timescales
  • investigate a technique for comparing the composition of limestones (eg carbonate content)
  • investigate differences between igneous rocks
  • learn about differences between volcanoes and relate this to processes of formation
  • describe and explain how sediment becomes sedimentary rock
  • describe the conditions under which metamorphic rock is formed
  • describe how igneous rocks crystallise from magma; relate crystal size to rate of cooling
  • describe some distinctive features of igneous, sedimentary and metamorphic rocks and use these to distinguish between the rock types
  • explain in terms of the particle model how different rates of cooling lead to different crystal sizes; bring together physical and chemical processes to explain the formation of different rock types and the rock cycle; relate composition to the process of formation

Its handy to know ...

  • know that there are rocks under the surface of the Earth and that soils come from rocks
  • can name some examples of rocks and describe their textures
  • can describe weathering processes and explain how sediment is formed
  • know that solids, liquids and gases are made of particles and about the differences between the way particles are arranged in solids and liquids

Some important words for you to understand, use and spell correctly

  • names of rock types, eg igneous, metamorphic, sedimentary
  • names of rocks, eg granite, pumice, shale
  • words and phrases describing properties of rocks, eg relative density, iron rich, crystals, aligned, porous
  • names of materials and processes associated with volcanic processes, eg magma, lava, volcanic ash, erupt

How is sedimentary rock formed?

  • that sedimentary rock can be formed by pressure from layers of sediment resulting in the compaction and cementation of grains
  • about some characteristics of sedimentary rocks
  • revise weathering and sedimentation eg the physical and chemical causes of weathering, that rocks consist of grains which fit together, and that over time layers of sediment accumulate.
  • the idea of compacting grains by squashing wet sand and observe the loss of water
  • show pictures of deep layers of sedimentary rock and think about the pressure at the bottom of a cliff, what is holding the grains together? Reminder that rocks are mixtures and establish that the ‘glue’ comes from minerals in the sediment that have dissolved and been left as the water evaporated
  • look at samples of other sedimentary rocks, eg chalk, limestone, shale, and identify some common characteristics.
  • name some sedimentary rocks, eg sandstone, chalk
  • describe characteristics of sedimentary rocks, eg non-interlocking textures, porous, contain fossils
  • explain that the pressure exerted by deep strata will be very great
  • explain that sedimentary rock is formed as the grains are compacted and glued together

Are all limestones different?

  • that rocks are mixtures of varying composition
  • that the composition of a limestone is related to the process of formation eg brown limestone; observe differences between them, eg appearance, porosity
  • limestones are carbonate-rich rocks, but may contain other components, remind pupils of how carbonates react with acids and help them to plan a way of comparing the carbonate content of two samples, eg by weighing samples before and after reacting with acid, measuring the volume of acid required to completely react with the carbonate, how they were formed, eg accumulation of fossil fragments, by chemical precipitation, and why, eg mud-free lagoon, reef
  • generalise that rocks are mixtures and vary in composition
  • relate the composition of limestone to the process of formation

What is different about metamorphic rocks?

  • that increasing temperature and pressure can cause some rocks to change in the solid state
  • that metamorphic rocks are formed from pre-existing rocks during metamorphism, as a result of high pressure and/or high temperature (metamorphism means ‘changing form’)
  • examine samples of metamorphic rock and compare them with the sedimentary rocks from which they were formed, eg limestone and chalk with marble, sandstone with quartzite, shale with slate, note alignment of grains, eg in slate
  • name some metamorphic rocks
  • describe how metamorphic rocks differ from sedimentary rocks, eg the crystals may be aligned, they may be less porous, fossils may or may not be distorted, no grains may be visible, the rock may be harder
  • metamorphic rocks can be formed from igneous, sedimentary or metamorphic rock, but the changes from sedimentary to metamorphic are most easily seen. Sedimentary rocks that contain ‘platey’ minerals, eg shale, may change to show alignment of crystals, as in slate. Other metamorphic rocks, eg marble and quartzite, leave a ‘sugary’ texture because the minerals from which they were formed resist pressure equally in all directions

Where do igneous rocks come from?

  • so far considered two kinds of rock, sedimentary and metamorphic, but there is a third type, igneous rock
  • name some igneous rocks, these are formed from cooled and crystallised from magma from volcanic eruptions eg granite, gabbro, basalt
  • that the rate of cooling and crystallisation determines the grain size in an igneous rock
  • to explain observations in terms of the particle model
  • volcanic eruptions, magma can flow out as lava or be blasted out as ash and compare the resulting rocks
  • the effects of cooling rates on crystal size, the longer this goes on, the larger and fewer the crystals will become and explain in terms of the particle model of matter.
  • given a variety of rock samples and ask them to classify them into types of rock, eg igneous and non-igneous, and then to subdivide them into rapid- and slow-cooling types, and/or suggesting where they were formed, eg obsidian (glasslike, very fast cooling on surface); pumice (gas bubbles, fast cooling on surface); basalt (small crystals, moderate cooling near surface) gabbro/granite (large crystals, slow cooling in the Earth)
  • relate the size of grain to where the crystal was formed, eg it has small crystals, so it cooled fast and was probably formed near the Earth’s surface
  • the relative densities of the two rock samples using displacement and what could cause the difference in their densities? investigate the relative densities of other igneous rocks, eg obsidian, basalt, and to use what they know about the difference in relative density to decide whether they are more like granite or gabbro.
  • Where appropriate, present pupils with data about the relative density, mineral composition and chemical composition of gabbro and granite and help them to use the data to show that granite rocks are relatively silica rich and gabbroic rocks are relatively iron rich.
  • use data to assign igneous rocks to one of two main groups, dense iron-rich or less dense silica-rich

What is the rock cycle?

  • that the rock cycle links together the processes of rock formation
  • how the rock cycle provides a continuous supply and transformation of Earth materials
  • review knowledge of the three kinds of rock and match descriptions with rock types
  • reminder  of how sedimentary rocks are formed and how these can be changed into metamorphic rock
  • where does igneous rock comes from and describe the process whereby existing rocks melt under high pressure and at high temperature to form magma
  • Lay out labelled diagram of the rock cycle, eg sediments, metamorphic rocks, magma, rocks at the Earth’s surface, and labels for processes, eg deposition, metamorphism, melting, and examples of the products, eg sand, limestone, slate etc. in the right places
  • describe the evidence for rocks melting
  • identify and link the rock-forming processes

KS3 Chemistry About the unit

In this unit pupils:

  learn about the major rock-forming processes

  learn how rock-forming processes are linked by the rock cycle

  use the concept of rock texture as one of the key characteristics of igneous, sedimentary and metamorphic rocks

  relate processes observed in other contexts, eg crystallisation, to processes involved in the rock cycle

  consider processes operating on different timescales

In scientific enquiry pupils:

  model rock-forming processes

  investigate a technique for comparing the composition of limestones, evaluating different approaches

  investigate differences between igneous rocks using both first-hand and secondary data

KS3 Chemistry Where the unit fits in

This unit builds on unit 8G ‘Rocks and weathering’ and work on the particle model in
unit 7G ‘Particle model of solids, liquids and gases’ and in unit 8I ‘Heating and cooling’. Work on carbonates relates to work on acids and carbonates in unit 7F ‘Simple chemical reactions’. Rocks as mixtures are considered in unit 8F ‘Compounds and mixtures’. There are also connections with work on fossil fuels in unit 7I ‘Energy resources’.

This unit relates to work in unit 2 ‘The restless earth – earthquakes and volcanoes’, unit 13 ‘Limestone landscapes of England’ and unit 21 ‘Virtual volcanoes and internet earthquakes’ in the geography scheme of work.

This unit, together with unit 8G ‘Rocks and weathering’, provides the foundation for work in key stage 4 on rock formation and deformation and processes involving tectonic plates.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: suggest how they could investigate the carbonate content of a limestone rock; interpret data from secondary sources and their own observations of rocks and about differences between volcanoes and relate this to processes of formation; draw conclusions from their data and describe how their own conclusions are consistent with the evidence obtained

some pupils will not have made so much progress and will: describe the results of their investigation; use data from secondary sources and identify differences between different rocks

some pupils will have progressed further and will: evaluate data obtained, indicating how confident they are in their conclusions

in terms of materials and their properties

most pupils will: describe and explain how sediment becomes sedimentary rock; describe the conditions under which metamorphic rock is formed and how igneous rocks crystallise from magma; relate crystal size to rate of cooling; describe some distinctive features of igneous, sedimentary and metamorphic rocks and use these to distinguish between the rock types

some pupils will not have made so much progress and will: name the three types of rock and give some examples of each; describe some characteristics of each rock type; explain that high temperature and pressure can change existing rocks into different types of rocks

some pupils will have progressed further and will: explain in terms of the particle model how different rates of cooling lead to different crystal sizes; bring together physical and chemical processes to explain the formation of different rock types and the rock cycle; relate composition to the process of formation

KS3 Chemistry Prior learning

It is helpful if pupils:

  know that there are rocks under the surface of the Earth and that soils come from rocks

  can name some examples of rocks and describe their textures

  can describe weathering processes and explain how sediment is formed

  know that solids, liquids and gases are made of particles and about the differences between the way particles are arranged in solids and liquids

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity.  In this unit pupils:

  plan and carry out their own investigations into the composition of limestone and into the differences between igneous rocks

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide.  Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  names of rock types, eg igneous, metamorphic, sedimentary

  names of rocks, eg granite, pumice, shale

  words and phrases describing properties of rocks, eg relative density, iron rich, crystals, aligned, porous

  names of materials and processes associated with volcanic processes, eg magma, lava, volcanic ash, erupt

Through the activities pupils could:

  describe and evaluate how work was undertaken and what led to the conclusions

KS3 Chemistry Resources

Resources include:

  a collection of rocks, either one available commercially or one compiled by the department, eg conglomerates, sandstone, limestone, chalk, mudstone, shale, slate, marble, quartz, granite, gabbro, basalt, pumice, obsidian, some of which are typical of their type and some of which have unusual features

  data showing relative density and composition of igneous rocks, eg basalt, pumice, obsidian

  data showing where volcanoes of different kinds are found

  cards/labels showing processes and examples of products of the rock cycle

KS3 Chemistry Out-of-school learning

Pupils could:

  read books about the Earth and its history and newspaper articles about weather conditions (floods and high winds) or volcanic eruptions

  watch television programmes or videos, including feature films, about the Earth, which help them understand how rocks are formed

  visit science museums to see displays about the Earth and its rocks and simulations, which will help them to imagine the effects of earthquakes and the forces involved

  visit other museums and art galleries, garden centres and builders’ yards, to see how rocks are used

  read science fiction texts about earlier geological ages

  visit the seashore to observe shingle, sand, river estuaries and cliffs, or hills to observe peat and rock formations, eg limestone pavements

   KS3 Chemistry: How is sedimentary rock formed?

   that sedimentary rock can be formed by pressure from layers of sediment resulting in the compaction and cementation of grains

   about some characteristics of sedimentary rocks

   Review what pupils know about different rocks, weathering and sedimentation by asking them a series of questions related to photographs and specimens. Establish key points, eg the physical and chemical causes of weathering, that rocks consist of grains which fit together, and that over time layers of sediment accumulate.

   Introduce the idea of compacting grains by showing pupils the effect of squashing wet sand and asking them to observe the loss of water; show them pictures of deep layers of sedimentary rock and ask them to think about the pressure at the bottom of a cliff. Ask pupils to look at some damp sand and some sandstone with a hand lens, or under the microscope, and look for clues about what is holding the grains together. Remind pupils that rocks are mixtures and establish that the ‘glue’ comes from minerals in the sediment that have dissolved and been left as the water evaporated. Show pupils samples of other sedimentary rocks, eg chalk, limestone, shale, and identify some common characteristics.

  name some sedimentary rocks, eg sandstone, chalk

  describe characteristics of sedimentary rocks, eg non-interlocking textures, porous, contain fossils

  explain that the pressure exerted by deep strata will be very great

  explain that sedimentary rock is formed as the grains are compacted and glued together

   If this half unit is taught directly after unit 8G ‘Rocks and weathering’, a similar activity will just have been carried out.

   Pupils will not need to recall the details of compaction and cementation but will need to be aware that it occurs.

   Extension: pupils could investigate compaction and cementation by making pellets of sand mixed with water, clay and plaster of Paris in a syringe with the end cut off, and compare the results.

   KS3 Chemistry: Are all limestones different?

   to use preliminary work to find out whether a possible approach is practicable

   to describe and evaluate how the work was undertaken and what led to the conclusions

   that rocks are mixtures of varying composition

   that the composition of a limestone is related to the process of formation

   Show pupils some examples of different limestone, eg brown limestone; ask them to describe some differences between them, eg appearance, porosity. Explain that they are going to find a way of investigating differences in composition.

   Establish that limestones are carbonate-rich rocks, but may contain other components. Remind pupils of how carbonates react with acids and help them to plan a way of comparing the carbonate content of two samples,
eg by weighing samples before and after reacting with acid, measuring the volume of acid required to completely react with the carbonate. Ask pupils to think about what they are planning to do and perhaps try out some ideas. Ask groups of pupils to explain and evaluate their methods and what they found out, eg using a flip chart or overhead projector (OHP). Where appropriate, extend the work by providing pupils with data about the carbonate content of different limestones and information about how they were formed, eg accumulation of fossil fragments, by chemical precipitation, and why, eg mud-free lagoon, reef. Ask pupils to use the data to make generalisations about composition and formation.

  describe some observable differences between limestones

  suggest an approach to the problem and try it out, identifying difficulties, eg you have to dry the limestone before you weigh it again, it’s better if you crush it up so that the acid reaches all of it

  describe and evaluate their approaches indicating problems they encounter

  generalise that rocks are mixtures and vary in composition

  relate the composition of limestone to the process of formation

   Pupils will have explored the effect of acids on carbonates in unit 7F ‘Simple chemical reactions’. This will be revisited in unit 9E ‘Reactions of metals and metal compounds’ and in unit 9G ‘Environmental chemistry’.

   In unit 7I ‘Energy resources’ pupils will have had opportunities to use a balance.  In unit 8F ‘Compounds and mixtures’ pupils will have considered differences between pure compounds and mixtures.

   All limestones contain carbonates and are at least 50% calcium carbonate.

Safety  

eye protection will be needed when acids are used. Teachers will need to check pupils’ plans for health and safety before practical work starts. Use acids in concentrations that present as low a hazard as possible, eg hydrochloric acid is low hazard below 2 mol dm-3, sulphuric acid below 0.5 mol dm-3, nitric acid below 0.1 mol dm-3

   KS3 Chemistry:  What is different about metamorphic rocks?

   that increasing temperature and pressure can cause some rocks to change in the solid state

   that metamorphic rocks are formed from pre-existing rocks during metamorphism, as a result of high pressure and/or high temperature

   Explain, with illustrations, theories about the formation of metamorphic rocks, and ask pupils to examine samples of metamorphic rock and compare them with the sedimentary rocks from which they were formed,
eg limestone and chalk with marble, sandstone with quartzite, shale with slate
. Using slides or photographs, show pupils illustrations of the alignment of grains, eg in slate. Ask pupils to choose one pair of sedimentary and metamorphic rocks, describe the differences between them and explain how the metamorphic rock was formed.

  name some metamorphic rocks

  describe how metamorphic rocks differ from sedimentary rocks, eg the crystals may be aligned, they may be less porous, fossils may or may not be distorted, no grains may be visible, the rock may be harder

  describe the processes by which a particular metamorphic rock is formed

   Pupils may not be aware that metamorphism means ‘changing form’.

   It may be helpful for some pupils if the processes and types of rock are presented on a series of cards or using ICT and pupils are asked to arrange them.

   Metamorphic rocks can be formed from igneous, sedimentary or metamorphic rock, but the changes from sedimentary to metamorphic are most easily seen. Sedimentary rocks that contain ‘platey’ minerals, eg shale, may change to show alignment of crystals, as in slate. Other metamorphic rocks, eg marble and quartzite, leave a ‘sugary’ texture because the minerals from which they were formed resist pressure equally in all directions.

    KS3 Chemistry: Where do igneous rocks come from?

   that igneous rocks crystallise from magma

   that the rate of cooling and crystallisation determines the grain size in an igneous rock

   to explain observations in terms of the particle model

   to draw conclusions from observations of rock samples

   Show pupils a video clip of a volcanic eruption, asking them to observe that magma can flow out as lava or be blasted out as ash, and compare the resulting rocks. Ask them to suggest the origin of the magma. Remind pupils that they have considered two kinds of rock, sedimentary and metamorphic. Explain that there is a third type, igneous rock.

   Ask pupils to find out how they can make larger or smaller crystals from melted salol to illustrate the behaviour of cooling magma. Establish the link between cooling rates and size of crystals produced.

   Model the effects of cooling rates on crystal size, with pupils representing atoms free to move around in an open space, as in a melt. On cooling, indicated by a signal, pupils stick together to begin forming crystals. The longer this goes on, the larger and fewer the crystals will become. Ask pupils to relate differences in crystal size (number of pupils bonded) and number of crystals (number of groups of pupils) to cooling time and to explain in terms of the particle model of matter.

   Provide pupils with a variety of rock samples and ask them to classify them into types of rock, eg igneous and non-igneous, and then to subdivide them into rapid- and slow-cooling types, and/or suggesting where they were formed, eg

    obsidian (glasslike, very fast cooling on surface)

    pumice (gas bubbles, fast cooling on surface)

    basalt (small crystals, moderate cooling near surface)

    gabbro/granite (large crystals, slow cooling in the Earth)

  name some igneous rocks

  describe how hot liquid magma can flow out of volcanoes as lava and solidify or be blown out as ash which settles

  describe how some rocks are formed when magma solidifies and these are called igneous rocks

  relate speed of cooling to crystal size and explain this in terms of the particle model

  relate the size of grain to where the crystal was formed, eg it has small crystals, so it cooled fast and was probably formed near the Earth’s surface

   The relationship between the three types of rock will be dealt with at the end of this unit.

   Pupils could access website references for currently active volcanoes, eg
www.geo.mtu.edu/volcanoes/world.html or www.volcano.und.nodak.edu

   Particle explanations of changes of state are covered in unit 8I ‘Heating and cooling’.

   Extension: pupils could simulate the cooling of magmas in the Earth’s crust and on the surface by datalogging the cooling curves of a beaker of boiling water surrounded by sand and a tray of boiling water. Ask pupils to explain the differences in the cooling curves and relate them to differences between different samples of rock and where these were found.

Safety  

salol is low hazard, but eye protection should be worn

  KS3 Chemistry:  Where do igneous rocks come from? (Cont.)

   to use first-hand and secondary sources of data to investigate differences between igneous rocks

   Present samples of granite and gabbro to pupils and ask them to suggest evidence for their origin as igneous rocks.

   Show pupils how to find the relative densities of the two rock samples using displacement and ask pupils what could cause the difference in their densities. Ask pupils to investigate the relative densities of other igneous rocks, eg obsidian, basalt, and to use what they know about the difference in relative density to decide whether they are more like granite or gabbro.

   Where appropriate, present pupils with data about the relative density, mineral composition and chemical composition of gabbro and granite and help them to use the data to show that granite rocks are relatively silica rich and gabbroic rocks are relatively iron rich.

  use data to assign igneous rocks to one of two main groups, dense iron-rich or less dense silica-rich

  show how relative density relates to composition of igneous rocks

  evaluate how well their data supports their conclusions

   Data about location and type of volcano can be found on the internet at, eg
www.geo.mtu.edu/volcanoes /world.html or www.volcano.und.nodak.edu

   Extension: pupils could be asked to find out about specific volcanic eruptions and their effects on the local population and environment. Teachers will be aware that sensitivity is needed where pupils have relatives or friends living in volcanic areas.

   Extension: pupils could be asked to use secondary sources to locate where volcanoes with silica-rich rocks (continents) and volcanoes with iron-rich rocks (oceans) are found. They could then identify the location of explosive volcanoes (with violent and generally unpredictable eruptions producing ash and pumice, not lava), eg Montserrat and moderate volcanoes (with streaming lava flows and frequent eruptions producing basalt lavas, sometimes with gas bubbles), eg Hawaii. Discuss how strongly the evidence supports the link between the chemical composition of magma and the types of volcanic activity.

    What is the rock cycle?

   that the rock cycle links together the processes of rock formation

   how the rock cycle provides a continuous supply and transformation of Earth materials

   Review pupils’ knowledge of the three kinds of rock through asking questions about processes and asking pupils to match descriptions with rock types. Remind them of how sedimentary rocks are formed and how these can be changed into metamorphic rock. Pose a question about where igneous rock comes from and describe the process whereby existing rocks melt under high pressure and at high temperature to form magma.

   Lay out labels of the products of the rock cycle, eg sediments, metamorphic rocks, magma, rocks at the Earth’s surface, and ask pupils to place labels for processes, eg deposition, metamorphism, melting, and examples of the products, eg sand, limestone, slate, a photograph of a volcano, a photograph of a mountain, in the right places.

  describe the evidence for rocks melting

  identify and link the rock-forming processes

   As an alternative, pupils could be presented with an outline flow diagram of the rock cycle, together with phrases describing processes and rock types, to insert at appropriate places on the diagram. Ask pupils to work in groups to fit the phrases in the correct places in the diagram. Discuss with pupils, asking questions to test their understanding.

    KS3 Chemistry: Reviewing work

   to relate key ideas about geological changes to each other

   Ask pupils to produce and present, on overhead transparencies (OHTs), an interpretation of the rock cycle, eg through a cartoon, story of the life of a rock (or two or three).

  describe the continuous process of the rock cycle

   As an alternative, pupils could be asked to indicate on a diagram, or other illustration of the rock cycle, which of the processes are biological, eg soil production, formation of fossils, which may be chemical,
eg weathering, and which may be physical, eg transportation, metamorphism, melting.

TOP OF PAGE and ALL INDEX LINKS

  Doc Brown's KS3 Chemistry KS3 SCIENCE Unit 9E Reactions of metals and metal compounds


KS3 Chemistry In this unit you should learn

  • about the properties of metals and non-metals
  •  that different acids react in similar ways with metals, with metal carbonates and with metal oxides
  • how to represent elements by symbols and compounds by formulae
  • use word and symbol equations to describe these reactions
  • describe patterns in qualitative data about reactions
  • use patterns in reactions to make predictions about other reactions
  • devise and evaluate a method for preparing a sample of a specified salt
  • make observations and use these to identify similarities in chemical reactions; use preliminary work to decide on a method for preparing a salt and suggest ways in which their method could be improved
  • describe how metals react with acids and how acids react with metal carbonates, metal oxides and alkalis; identify evidence which indicates that a chemical reaction has taken place; represent reactions by word equations, identify patterns in these and produce general equations; name a variety of salts and describe the uses of some of them

Its handy if you ..

  • can name some metals, understanding that they are elements, and can give some of their characteristics
  • know that atoms join together in different ways when chemical reactions take place
  • have represented some elements and compounds by symbols and formulae
  • understand that chemical reactions can be represented by word, particle and symbol equations
  • have carried out tests to identify hydrogen and carbon dioxide

Some important words for you to understand, use and spell correctly ..

  • names of compounds, including salts, eg magnesium sulphate, copper carbonate, copper nitrate, sodium chloride, potassium nitrate, recognising that the whole name is needed to specify a compound
  • words with different meanings in scientific and everyday contexts eg salt, reaction, product
  • words and phrases relating to scientific enquiry, eg visible change, evidence of reaction

Why are metals useful?

  • that metals are good conductors of heat and electricity
  • that most non-metallic elements are poor conductors of heat and electricity
  • there is a range of metals, lots of different uses, and where they are found?
  • Where do we get metals (iron, zinc, copper, lead, gold, silver) from, what are they used for?
  • make a comparison of the properties of non-metals and metals and to explain what makes metals useful eg consider the properties -  heat/electricity conduction, melting/boiling points, density, malleability (how easy to bend and shape), dull/shiny, strength
  • there are similarities in the ways in which metals react chemically
  • identify carbon (in graphite form) as a non-metallic conductor
  • make some generalisations about the properties of metals which make them useful, eg they are hard, they can be flexible
  • don't confuse non-metallic elements with other non-metallic materials
  • consider the chemical reactions of metals and acids and to begin to represent these symbolically
  • find out about ways in which metals have been used in the past, eg in jewellery

What happens when metals react with acids?

  • that some metals (eg Zn, Fe, Mg, Ca) react with dilute acids to form salts and release hydrogen
  • signs of reaction, colour changes, bubbles, and to carry out a test for hydrogen
  • to represent the reactions of metals with dilute acids by word equations and explain the similarities between them eg to identify patterns in reactions between metals and dilute acids
  • to use patterns in reactions to make predictions about other reactions, predict that hydrogen and the appropriate salt will be made as a result of the reaction
  • use the formulae of the reactants and products to explain how atoms join in different ways as a result of the reaction
  • When calcium is used with sulphuric acid, there will be very little reaction because insoluble calcium sulphate is formed.

How do acids react with metal carbonates?

  • that acids react with metal carbonates, producing water, carbon dioxide and a salt
  • that production of new materials and energy changes are evidence of chemical reactions
  • what happens when acids, eg hydrochloric, sulphuric, nitric, react with a range of carbonates, eg sodium carbonate, calcium carbonate, copper carbonate
  • what is similar about the reactions? use word equations - produce general word equation
  • is a gas made? how do you know and what is it? are there colour changes? does the test tube get hot or cold? ie record evidence of a chemical reaction taking place.
  • given the formulae of a variety of metal carbonates and their corresponding chlorides, sulphates and nitrates, and invite pupils in groups to work out the products of some reactions between metal carbonates and acids
  • note that nitrate and sulphate, and sometimes carbonate, are ‘groups’ of atoms which often stay together in chemical reactions
  • begin to represent these reactions by symbol equations.

What evidence is there of a chemical reaction between acids and metal oxides?

  • that acids react with metal oxides, producing a salt and water, general word equation
  • that production of the salt is evidence of a chemical reaction, colour changes
  • to represent reactions of acids with metal oxides by word equations (pattern, formulae help)
  • carry out a reaction between a metal oxide and an acid (preferably one that produces a coloured salt, eg copper sulphate) - evidence that a chemical reaction has taken place, separate any excess metal oxide by filtration apparatus, and evaporate the water, compare the salt formed with a stock sample and original oxide
  • why this reaction did not produce bubbles?
  • what happens to the pH of the acid when the metal oxide is added?
  • begin practise writing formulae and symbol equations.

What is a salt?

  • that when an alkali is added to an acid, neutralisation takes place, word equations to represent this
  • how to obtain a neutral solution from an acid and an alkali
  • the hazards associated with alkalis and acids
  • use of universal indicator to determine the acidity or alkalinity of a solution, neutralisation and a neutral solution is one with pH7 and that neutralization is a chemical reaction, everyday examples of neutralisation
  • neutralise hydrochloric acid with potassium hydroxide or sodium hydroxide and to find out exactly how much to add with an appropriate technique (indicator, pH probe, burette, measuring cylinder?)
  • how will you know when all the acid has reacted? how will you separate any unreacted solid? what will you do to try to get large crystals?
  • potassium chloride or sodium chloride is formed, that sodium chloride is common salt and is an example of the class of compounds called ‘salts’
  • identify the pattern in word equations and produce a general equation, eg acid + alkali => salt + water
  • further opportunities for some pupils to practise writing formulae and symbol equations
  • that there are many different salts and many salts are useful compounds
  • the names of a variety of salts  eg a part comes from a metal and a part comes from an acid, find out the uses of some salts, eg sodium stearate, potassium nitrate, copper sulphate, calcium phosphate, iron sulphate, magnesium sulphate, silver nitrate.

KS3 Chemistry About the unit

In this unit pupils:

  explore the properties of metals and non-metals

  learn that different acids react in similar ways with metals, with metal carbonates and with metal oxides

  represent elements by symbols and compounds by formulae

  use word and symbol equations to describe these reactions

In scientific enquiry pupils:

  describe patterns in qualitative data about reactions

  use patterns in reactions to make predictions about other reactions

  devise and evaluate a method for preparing a sample of a specified salt

KS3 Chemistry Where the unit fits in

This unit builds on unit 8E ‘Atoms and elements’ and unit 8F ‘Compounds and mixtures’.

In unit 7E ‘Acids and alkalis’, pupils will have observed neutralisation reactions, and in unit 7F ‘Simple chemical reactions’, they will have identified that there are chemical reactions between acids and metals and between acids and carbonates. However, they are unlikely to have considered the other products of these reactions. With some pupils, teachers may wish to concentrate on some of the new topics, extending activities, and with others to spend more time on revision of previous work.

This unit lays the foundation for unit 9F ‘Patterns of reactivity’.

KS3 Chemistry Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: make observations and use these to identify similarities in chemical reactions; use preliminary work to decide on a method for preparing a salt and suggest ways in which their method could be improved

some pupils will not have made so much progress and will: make observations of chemical reactions, and show that there are patterns in these; identify where they found difficulties in preparing a salt

some pupils will have progressed further and will: explain the steps they took to prepare a high-quality sample of a salt

in terms of materials and their properties

most pupils will: describe how metals react with acids and how acids react with metal carbonates, metal oxides and alkalis; identify evidence which indicates that a chemical reaction has taken place; represent reactions by word equations, identify patterns in these and produce general equations; name a variety of salts and describe the uses of some of them

some pupils will not have made so much progress and will: identify that hydrogen is produced when many metals react with acids, and carbon dioxide when acids react with carbonates, and describe tests for hydrogen and carbon dioxide; state that the production of a new material is evidence of a chemical reaction

some pupils will have progressed further and will: represent chemical compounds by formulae and combine these into symbol equations; use knowledge of reactions to make predictions about other reactions

KS3 Chemistry Prior learning

It is helpful if pupils:

  can name some metals, understanding that they are elements, and can give some of their characteristics

  know that atoms join together in different ways when chemical reactions take place

  have represented some elements and compounds by symbols and formulae

  understand that chemical reactions can be represented by word, particle and symbol equations

  have carried out tests to identify hydrogen and carbon dioxide

KS3 Chemistry Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  explore the properties of metallic and non-metallic elements

  use solutions of acids, alkalis and metal salts, which may be hazardous

  evaporate salt solutions prepared in a variety of ways

  plan and carry out an investigation into the preparation of a salt

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

KS3 Chemistry Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  names of compounds, including salts, eg magnesium sulphate, copper carbonate, copper nitrate, sodium chloride, potassium nitrate, recognising that the whole name is needed to specify a compound

  words with different meanings in scientific and everyday contexts,
eg salt, reaction, product

  words and phrases relating to scientific enquiry, eg visible change, evidence of reaction

Through the activities pupils could:

  organise content into a whole piece of writing with the relationship between points and/or paragraphs clearly signalled

  structure paragraphs to develop points by using evidence and additional facts

KS3 Chemistry Resources

Resources include:

  information about metals

  cards showing names of acids, alkalis, metal carbonates, metal oxides and metals

  cards showing names of salts that can be safely prepared

  information about hazards of salts and starting materials for their preparation

  two accounts of the preparation of a salt, one that effectively evaluates the method and product, eg mass, appearance of crystals, and one that does not

  secondary sources providing information about the uses of salts

KS3 Chemistry Out-of-school learning

Pupils could look for examples of:

  metal corrosion in the locality

  the use of metal compounds in everyday products

    KS3 Chemistry: Why are metals useful?

   that metals are good conductors of heat and electricity

   that most non-metallic elements are poor conductors of heat and electricity

   about the range of metals, their uses and where they are found

   to use and combine data from a variety of information sources

   to organise facts/ideas/ information into an appropriate sequence

   Provide pupils with a range of questions about metals and non-metals, eg

    Are metals good conductors of heat/electricity?

    Are non-metals non-conductors?

    Are non-metals all gases?

    Where do we get metals (iron, zinc, copper, lead, gold, silver) from?

    What are they used for?

    Suggest sources of information they could use, eg databases, reference books, practical activities.

   Ask different groups to explore different questions and to produce a factsheet about a particular element or property. Help pupils use these to make a comparison of non-metals and metals and to explain what makes metals useful.

   Explain to pupils that there are similarities in the ways in which metals react chemically and that they are going to find out more about these in this unit.

  contrast the conductivity of metals and non-metals

  identify graphite as a non-metallic conductor

  produce an information sheet that is correct and well sequenced and contains appropriate information

  make some generalisations about the properties of metals which make them useful, eg they are hard, they can be flexible

   Pupils often confuse non-metallic elements with other non-metallic materials. It is helpful to restrict this activity to elements.

   Some pupils will need to do more work to consolidate their ideas about differences between metals and non-metallic elements, while others will be able to move on to consider the chemical reactions of metals and acids and to begin to represent these symbolically. Teachers will need to decide which parts of the unit to emphasise.

   This activity offers an opportunity to construct a class database about metals and non-metals. This could be used as a starting point for another class.

   Extension: pupils could be asked to find out about ways in which metals have been used in the past, eg in jewellery.

Safety

– if practical activities are included, appropriate risk assessments must be followed

    KS3 Chemistry: What happens when metals react with acids?

   that some metals react with dilute acids to form salts and release hydrogen

   to carry out a test for hydrogen

   to represent the reactions of metals with dilute acids by word equations

   to identify patterns in reactions between metals and dilute acids

   to use patterns in reactions to make predictions about other reactions 

   Demonstrate that a metal, eg zinc, reacts with both hydrochloric acid and sulphuric acid to produce a gas. Establish that the bubbles indicate that a gas is being formed, that this is a new material and that a chemical reaction is taking place. Show pupils the formulae for the two acids and ask them to suggest what the gas might be. Remind them of the test for hydrogen and demonstrate that hydrogen is formed.

   Ask pupils to find out whether similar reactions occur when other metals, eg magnesium, iron, react with hydrochloric acid and to record their results in a table. Establish that hydrogen is produced in each case and, using the names, symbols and formulae for the reactants and hydrogen, ask pupils to suggest what has happened to the metal and where the other product might be found. Using appropriate sample(s), show by evaporation that the salt remains in solution. Using the patterns in the equations, ask pupils to predict what will be made when calcium reacts with hydrochloric and sulphuric acids. Demonstrate the reactions, showing that hydrogen is made.

  identify the gas produced in the reaction between metals and acids as hydrogen

  write word equations for the reactions and explain the similarities between them

  use the formulae of the reactants and products to explain how atoms join in different ways as a result of the reaction

  predict that hydrogen and the appropriate salt will be made as a result of the reaction

   When calcium is used with sulphuric acid, there will be very little reaction because insoluble calcium sulphate is formed.

   From their work on this and the following activities, pupils could make a display showing equations for the reactions they have carried out and including samples of reactants and products.

   In unit 7F ‘Simple chemical reactions’ pupils will have explored the formation of hydrogen, but are less likely to have considered the other products of the reactions. The emphasis in this activity should be on the patterns in the products formed and in the equations.

 

Safety

0.4 mol dm-3 solutions of acid are suitable. Eye protection should be used. Ensure that excess metal is used so that the acids are not evaporated

If iron is used, some toxic hydrogen sulphide is likely to be produced

– use only one granule of calcium

    KS3 Chemistry: How do acids react with metal carbonates?

   that acids react with metal carbonates, producing carbon dioxide and a salt

   that production of new materials and energy changes are evidence of chemical reactions

   Ask pupils to explore what happens when acids, eg hydrochloric, sulphuric, nitric, react with a range of carbonates, eg sodium carbonate, calcium carbonate, copper carbonate. Prompt them with a series of questions, eg

    What is similar about the reactions?

    Is a gas made? How do you know and what is it?

    Are there colour changes?

    Does the test tube get hot or cold?

   Ask pupils to record their observations systematically and to record evidence of a chemical reaction taking place.

   Give pupils the formulae of a variety of metal carbonates and their corresponding chlorides, sulphates and nitrates, and invite pupils in groups to work out the products of some reactions between metal carbonates and acids. Help them to construct word equations. Collect and discuss their predictions, look for any patterns and establish the general word equation.

  identify the gas produced as carbon dioxide

  identify evidence for a chemical reaction, eg a gas is produced, the test tube is getting hot

  represent reactions by word equations

  identify the pattern in word equations and produce a general equation

   In unit 7F ‘Simple chemical reactions’ pupils are likely to have reacted acids with carbonates and tested for carbon dioxide produced, but are less likely to have considered the other products of the reaction. Pupils will have investigated different samples of limestone through their reaction with acid in unit 8H ‘The rock cycle’.

   Pupils will have considered burning/oxidation as a reaction in which energy is released in unit 7I ‘Energy resources’ and unit 8B ‘Respiration’. This unit is the first in which they will have considered energy release as indicative of a chemical reaction.

   In the activities in this unit, it may be helpful to emphasise that nitrate and sulphate, and sometimes carbonate, are ‘groups’ which often stay together in chemical reactions.

   Teachers may wish to help some pupils represent these reactions by symbol equations.

   Extension: pupils who have some familiarity with formulae and symbol equations could be given a short passage in a foreign language containing a number of equations. Their ability to explain it demonstrates the universality of chemical formulae and equations.

Safety

0.4 mol dm-3 solutions of acid are suitable. 0.4 mol dm-3 hydrochloric acid is low hazard, 0.4 mol dm-3 sulphuric acid is low hazard and 0.4 mol dm-3 nitric acid is irritant

     KS3 Chemistry: What evidence is there of a chemical reaction between acids and metal oxides?

   that acids react with metal oxides, producing a salt and water

   that production of the salt is evidence of a chemical reaction

   to represent reactions of acids with metal oxides by word equations 

   Demonstrate, or ask pupils to carry out, a reaction between a metal oxide and an acid (preferably one that produces a coloured salt, eg copper sulphate) and ask pupils for evidence that a chemical reaction has taken place. Separate any excess metal oxide, reminding pupils how to use filtration apparatus, and evaporate the water. Compare the salt formed with a stock sample.

   Help pupils to construct a word equation and, by using the formula, to identify the other product. Ask pupils to explain why this reaction did not produce bubbles. Give pupils the names of some other salts and ask them to suggest which acid and metal oxide would be needed to make them. Display suggestions and ask others to explain whether they are correct or not.

  identify evidence for a chemical reaction, eg crystals are made, which are a different colour from what we started with

  represent reactions by word equations

  identify the patterns in word equations and produce a general equation

   Extension: some pupils might investigate what happens to the pH of the acid when the metal oxide is added. This could provide an opportunity for datalogging using ICT.

   Extension: this offers further opportunities for some pupils to practise writing formulae and symbol equations.

Safety

0.4 mol dm-3 acid is suitable. Eye protection should be worn. Ensure pupils use excess oxide so that acid is not evaporated. Sometimes the reaction is very slow towards the end and not all of the acid is used up

do not use nickel oxide, which is toxic and a grade 1 carcinogen

    KS3 Chemistry: Checking progress

   to summarise how acids react with metals, metal carbonates and metal oxides 

   Ask pupils to work in groups to make individual cards with the names of each reactant, plus signs, arrows and the names of each product for two examples of each of these reactions: acids with metals, acids with metal carbonates, and acids with metal oxides. Each group then shuffles its cards and passes them to another group, which has to sort them into three pairs of word equations, representing three types of reaction of acids, and to write the word, symbol and general equations for their own reactions.