Oxford AQA International GCSE
Chemistry
Full syllabus for OxfordAQA IGCSE
Chemistry specification 9202
CHEMISTRY
(Oxford AQA International GCSE Chemistry)
ATOMIC STRUCTURE AND THE PERIODIC TABLE
(Oxford AQA International GCSE Chemistry)
Atoms are the building blocks of all materials and knowledge of atomic structure
and the periodic table are
fundamental to the learning associated with all the following sections.
Solids liquids and gases
(Oxford AQA International GCSE Chemistry)
a.
Matter can be classified in terms of the three states of matter.
Students should be familiar with states of matter and be able to name each
inter-conversion process. They
should be able to describe and explain their inter-conversion in terms of how
the particles are arranged and
their movement. They should understand the energy changes that accompany changes
of state.
b.
Evidence for the existence of particles can be obtained from simple experiments.
Students should be familiar with simple diffusion experiments such as Br2/air,
NH3/HCl,
KMnO4/water
A simple model of the atom
(Oxford AQA International GCSE Chemistry)
a.
All substances are made of atoms. A substance that is made of only one sort of
atom is called an element.
There are about 100 different elements. Elements are shown in the periodic
table.
b.
Atoms of each element are represented by a chemical symbol, eg O represents an
atom of oxygen.
Knowledge of the chemical symbols for elements other than those named in the
specification is
not
required.
c.
Atoms have a small central nucleus, made up of protons and neutrons, and around
which there are
electrons.
Students should be aware that the atomic model has changed over time.
d.
The relative electrical charges
and name of particle:
Proton
+1.
Neutron
0,
Electron
–1
e.
In an atom, the number of electrons is equal to the number of protons in the
nucleus. Atoms have no
overall electrical charge.
f.
The number of protons in an atom of an element is its atomic number. The sum of
the protons and
neutrons in an atom is its mass number.
Students will be expected to calculate the numbers of each sub-atomic particle
in an atom from its atomic
number and mass number.
g.
Atoms of the same element can have different numbers of neutrons; these atoms
are called isotopes of
that element.
h.
Atoms can be represented as shown in this example:
mass number
of
23,
atomic number
11
for sodium
i.
Electrons occupy particular energy levels. Each electron in an atom is at a
particular energy level (in a
particular shell). The electrons in an atom occupy the lowest available energy
levels (innermost available
shells).
Students may answer questions in terms of either energy levels or shells e.g.
diagram on the right.
Students should be able to represent the electronic structure of the first
twenty elements of the periodic
table in the following forms
j. The relative masses of protons, neutrons and electrons are:
Sub–atomic particle |
Relative mass |
Electric charge |
Comments |
Proton |
1 |
+1
(+ positive) |
In
the nucleus, a nucleon |
Neutron |
1 |
0
(zero) |
In the nucleus, a nucleon |
Electron |
1/1850 or 0.00055 very small |
–1
(– negative) |
NOT a nucleon. Electrons are arranged in energy levels or shells
in orbit around the nucleus |
k.
The relative atomic mass of an element (Ar) compares the mass of atoms of the element with the
12C
isotope (carbon-12). It is an average value for the isotopes of the element.
Students will not be expected to calculate relative atomic masses from isotopic
abundances.
THE PERIODIC
TABLE
(Oxford AQA International GCSE Chemistry)
a.
The periodic table is arranged in order of atomic (proton) number. Elements with
similar properties are in
columns, known as groups. The table is called a periodic table because similar
properties occur at regular
intervals.
Students should know that the current periodic table is based on the work of
Mendeleev.
b.
Elements in the same group in the periodic table have the same number of
electrons in their highest energy
level (outer electrons) and this gives them similar chemical properties.
Students should know that basing the periodic table on groups of elements with
similar properties has
allowed for the prediction of elements which were still to be discovered.
c.
The elements in Group 0 of the periodic table are called the noble gases. They
are unreactive because their
atoms have stable arrangements of electrons.
Students should know that the noble gases have eight electrons in their outer
energy level, except for
helium, which has only two electrons.
STRUCTURE, BONDING AND THE PROPERTIES OF MATTER
(Oxford AQA International GCSE Chemistry)
This section examines how atoms interact to form chemical bonds and how these
bonds determine the
properties and uses of materials.
Chemical bonds: ionic, covalent and metallic
(Oxford AQA International GCSE Chemistry)
a.
Compounds are substances in which atoms of two or more elements are chemically
combined.
b.
Chemical bonding involves either transferring or sharing electrons in the
highest occupied energy levels
(outer shells) of atoms in order to achieve the electron arrangement of a noble
gas.
c.
When atoms form chemical bonds by transferring electrons, they form ions. Atoms
that lose electrons
become positively charged ions. Atoms that gain electrons become negatively
charged ions. Ions have the
electron arrangement of a noble gas (Group 0). Compounds formed from metals and
non-metals consist of
ions.
Students should know that metals form positive ions, whereas non-metals form
negative ions.
Students should be able to represent the electron arrangement of ions in the
following form:
e.g. for the ionic compound sodium chloride, made up of the sodium ion (Na+)
and chloride ion (Cl-)
combination.

Students should be able to relate the charge on simple ions to the group number
of the element in the
periodic table
d.
The elements in Group 1 of the periodic table, the alkali metals, all react with
non-metal elements to form
ionic compounds in which the metal ion has a single positive charge.
Knowledge of the chemical properties of alkali metals is limited to their
reactions with non-metal elements
and water.
e.
The elements in Group 7 of the periodic table, the halogens, all react with
metals to form ionic compounds
in which the halide ions have a single negative charge.
Knowledge of the chemical properties of the halogens is limited to reactions
with metals and displacement
of less reactive halogens.
f.
An ionic compound is a giant structure of ions. Ionic compounds are held
together by strong electrostatic
forces of attraction between oppositely charged ions. These forces act in all
directions in the lattice and
this is called ionic bonding.
Students should be familiar with the structure of sodium chloride but do
not
need to know the structures of
other ionic compounds.
Students given appropriate information, should be able to draw or complete
diagrams to show how
elements form ions and ionic compounds.
g.
When atoms share pairs of electrons, they form covalent bonds. These bonds
between atoms are strong.
Some covalently bonded substances, such as H2,
Cl2
, O2, N2, HCl, H2O, NH3
and CH4, consist of simple
molecules. Others, such as diamond and silicon dioxide, have giant covalent
structures (macromolecules).
Students should be able to represent the covalent bonds in molecules such as
water, ammonia, hydrogen,
hydrogen chloride, methane and oxygen in the following forms:
e.g. for ammonia (NH3)
be familiar with these different styles
Students, given appropriate information, should be able to draw or complete
diagrams to show how
elements form covalent compounds by sharing electrons.
Students should be able to recognise other simple molecules and giant structures
from diagrams that
show their bonding
h.
Compounds formed from non-metals consist of molecules. In molecules, the atoms
are held together by
covalent bonds.
i.
Metals consist of giant structures of atoms arranged in a regular pattern.
j.
The electrons in the highest occupied energy levels (outer shell) of metal atoms
are delocalised and so
free to move through the whole structure. This corresponds to a structure of
positive ions with electrons
between the ions holding them together by strong electrostatic attractions. The
bonding in metals is
represented in the following form:
Showing the original neutral atoms and the actual ions and delocalised electrons
in the real metallic lattice of a metal crystal.
How bonding and structure are related to the properties of substances
a.
Ionic compounds have regular structures (giant ionic lattices) in which there
are strong electrostatic forces
of attraction in all directions between oppositely charged ions.
These compounds have high melting points and high boiling points because of the
large amounts of
energy needed to break the many strong bonds.
b.
When melted or dissolved in water, ionic compounds conduct electricity because
the ions are free to move
and carry the current.
Knowledge of the structures of specific ionic compounds other than sodium
chloride is
not
required.
c.
Substances that consist of simple molecules are gases, liquids or solids that
have relatively low melting
points and boiling points.
d.
Substances that consist of simple molecules have only weak forces between the
molecules
(intermolecular forces). It is these intermolecular forces that are overcome,
not the covalent bonds,
when the substance melts or boils.
Students need to understand that intermolecular forces are weak compared with
covalent bonds.
e.
Substances that consist of simple molecules do not conduct electricity because
the molecules do not have
an overall electric charge.
f.
Atoms that share electrons can also form giant structures or macromolecules.
Diamond and graphite
(forms of carbon) and silicon dioxide (silica) are examples of giant covalent
structures (lattices) of atoms.
All the atoms in these structures are linked to other atoms by strong covalent
bonds and so they have very
high melting points.
Students should be able to recognise other giant structures or macromolecules
from diagrams showing
their bonding.
g.
Metals conduct heat and electricity because of the delocalised electrons in
their structures.
Students should know that conduction depends on the ability of electrons to move
through the metal.
Structure and bonding in carbon
(Oxford AQA International GCSE Chemistry)
a.
The element carbon can form four covalent bonds.
b.
In diamond, each carbon atom forms four covalent bonds with other carbon atoms
in a giant covalent
structure, so diamond is very hard.
c.
In graphite, each carbon atom bonds to three others, forming layers. The layers
are free to slide over each
other because there are no covalent bonds between the layers and so graphite is
soft and slippery.
Extension Tier students should be able to explain the properties of graphite in
terms of weak forces
between the layers.
d.
In graphite, one electron from each carbon atom is delocalised. These
delocalised electrons allow
graphite to conduct heat and electricity.
Students should realise that graphite is similar to metals in that it has
delocalised electrons.
e.
Carbon can also form fullerenes with different numbers of carbon atoms.
Fullerenes can be used for drug
delivery into the body, in lubricants, as catalysts, and in nanotubes for
reinforcing materials, eg in tennis
racquets.
Students are only required to know that the structure of fullerenes is based on
hexagonal rings of carbon
atoms
NANOPARTICLES
(Oxford AQA International GCSE Chemistry)
Nanoscience refers to structures that are 1–100 nm in size, of the order of a
few hundred atoms. Nanoparticles
show properties different from those for the same materials in bulk and have a
high surface area to volume
ratio, which may lead to the development of new computers, new catalysts, new
coatings, highly selective
sensors, stronger and lighter construction materials, and new cosmetics such as
suntan creams and
deodorants.
Students should know what is meant by nanoscience and nanoparticles and should
consider some of the
applications of these materials, but do
not
need to know specific examples or properties.
Questions may be set on information that is provided about these materials and
relating their use to their
structure
CHEMICAL CHANGES
(Oxford AQA International GCSE Chemistry)
The group of materials known as metals are explored in more detail including how
atoms are rearranged to
form new substances in chemical reactions.
Metals
(Oxford AQA International GCSE Chemistry)
a.
Metals are useful materials because they are good conductors of heat and
electricity. They can be bent or
hammered into shape because the layers of atoms in metals are able to slide over
each other.
b.
An alloy is a mixture of at least two elements, at least one of which is a
metal. Alloys often have properties
that are different to the metals they contain. This makes them more useful than
the pure metals alone.
Steels are a mixture of iron with carbon and sometimes other metals.
Students may be given information on the composition of specific alloys so that
they can evaluate their
uses.
c.
Copper is useful for electrical wiring and plumbing because it has the following
properties:
•
it is a good conductor of heat and electricity
•
it can be bent but is hard enough to be used to make pipes or tanks
•
it does not react with water.
The reactivity series of metals
(Oxford AQA International GCSE Chemistry)
a.
Metals can be arranged in an order of their reactivity from their reactions with
water and dilute acids.
Students should be able to recall and describe the reactions, if any, of
potassium, sodium, lithium, calcium,
magnesium, zinc, iron and copper with water or dilute acids. Students should be
able, where appropriate,
to place them in order of reactivity.
b.
Displacement reactions involving metals and their compounds in aqueous solution
establish positions
within the reactivity series.
Students should be able to describe displacement reactions in terms of oxidation
and reduction, and to
write the ionic equations.
c.
Unreactive metals such as gold are found in the Earth as the metal itself but
most metals are found as
compounds that require chemical reactions to extract the metal.
d.
Metals that are less reactive than carbon can be extracted from their oxides by
reduction with carbon: for
example, iron oxide is reduced in the blast furnace to make iron.
Knowledge and understanding are limited to the reduction of oxides using carbon.
Knowledge of reduction is limited to the removal of oxygen.
Students should understand that oxidation can be described as the gain of oxygen
by a substance.
Details of the blast furnace are
not
required, but students should know the raw materials used and explain
the simple chemistry involved, including the use of equations.
Knowledge of the details of the extraction of other metals is
not
required. Examination questions may
provide further information about specific processes for students to interpret
or evaluate.
e.
Metals that are more reactive than carbon, such as aluminium, are extracted by
electrolysis of molten
compounds. The use of large amounts of energy in the extraction of these metals
makes them expensive.
Knowledge of the details of industrial methods of electrolysis is
not
required, other than the detail required
for aluminium.
f.
New ways of extracting copper from low-grade ores are being researched to limit
the environmental impact
of traditional mining.
Copper can be extracted by phytomining, or by bioleaching.
Students should know and understand that:
•
phytomining uses plants to absorb metal compounds and that the plants are burned
to produce ash that
contains the metal compounds
•
bioleaching uses bacteria to produce leachate solutions that contain metal
compounds.
Further specific details of these processes are
not
required.
g.
Copper can be obtained from solutions of copper salts by electrolysis.
Students should know the electrode material and be able to write the ionic half
equations for the reactions
occurring at both electrodes.
h.
Copper can be obtained from solutions of copper salts by displacement using
scrap iron.
Students should be able to describe this in terms of oxidation and reduction,
and to write the ionic equation.
i.
We should recycle metals because extracting them uses limited resources, and is
expensive in terms of
energy and in terms of effects on the environment.
Students are
not
required to know details of specific examples of recycling, but should
understand the
benefits of recycling in the general terms specified here
Metal carbonates
(Oxford AQA International GCSE Chemistry)
a.
The carbonates of magnesium, copper, zinc, calcium and lithium decompose on
heating (thermal
decomposition) in a similar way.
Students should be aware that not all carbonates of metals in Group 1 of the
periodic table decompose at
the temperatures reached by a Bunsen burner.
b.
Metal carbonates react with acids to produce carbon dioxide, a salt and water.
Electrolysis
(Oxford AQA International GCSE Chemistry)
a.
When an ionic substance is melted or dissolved in water, the ions are free to
move about within the liquid
or solution.
b.
Passing an electric current through ionic substances that are molten, eg lead
bromide, or in solution breaks
them down into elements. This process is called electrolysis and the substance
broken down is called the
electrolyte.
c.
During electrolysis, positively charged ions move to the negative electrode (the
cathode), and negatively
charged ions move to the positive electrode (the anode).
Required practical:
Investigate the products at the anode and cathode in the electrolysis of copper
sulfate solution.
d.
Oxidation and reduction can be defined as the loss and gain of electrons
respectively.
e.
At the cathode, positively charged ions gain electrons; at the anode, negatively
charged ions lose
electrons.
f.
Reactions at electrodes can be represented by half equations, for example:
2Cl
–
→
Cl2
+ 2e–
or
2Cl–
– 2e–
→
Cl2
Students should be able to write half equations for the reactions occurring at
the electrodes during
electrolysis, and may be required to complete and balance supplied half
equations.
g.
If there is a mixture of ions:
•
at the cathode, the products formed depend on the reactivity of the elements
involved
•
at the anode, the products formed also depend on the relative concentrations of
the ions present.
h.
Electrolysis is used to electroplate objects. This may be for reasons such as
appearance, durability and
prevention of corrosion. It includes copper plating and silver plating.
i.
Aluminium is manufactured by the electrolysis of a molten mixture of aluminium
oxide and cryolite.
Aluminium forms at the negative electrode and oxygen at the positive electrode.
The positive electrode is
made of carbon, which reacts with the oxygen to produce carbon dioxide.
Students should understand why cryolite is used in this process.
Students should be aware that large amounts of energy are needed in the
extraction process.
j.
The electrolysis of sodium chloride solution produces hydrogen and chlorine.
Sodium hydroxide solution
is also produced. These are important reagents for the chemical industry, eg
sodium hydroxide for the
production of soap and chlorine for the production of bleach and plastics.
Students should be able to explain, using ideas related to reactivity, why each
of these products is
produced
CHEMICAL ANALYSIS
(Oxford AQA International GCSE Chemistry)
This section focuses on developing practical skills in chemistry which identify
substances and reinforces the
idea of a pure substance as consisting of one substance only.
Purity and chromatography
(Oxford AQA International GCSE Chemistry)
a.
A pure element or compound contains only one substance, with no other substances
mixed in.
Students should be able to identify substances and assess their purity from
melting point and boiling point
information.
b.
Measures of purity are important in everyday substances such as foodstuffs and
drugs.
c.
A mixture consists of two or more elements or compounds not chemically combined
together. The
chemical properties of each substance in the mixture are unchanged. It is
possible to separate the
substances in a mixture by physical methods, including distillation, filtration
and crystallisation.
d.
Paper chromatography can be used to analyse substances present in a solution, eg
food colourings and
inks/dyes.
Students should be able to describe how to carry out paper chromatography
separations and
Extension
Tier students should be able to describe how the components of a mixture can be
identified using Rf
values.
They have to be aware that solvents other than water can be used.
e.
Chromatography involves a stationary and a mobile phase and separation depends
on the relative
solubilities of the components.
Students should be able to suggest chromatographic methods for distinguishing
pure from impure
substances.
IDENTIFICATION OF COMMON GASES
(Oxford AQA International GCSE Chemistry)
a.
A pop is heard when a lighted splint is placed near hydrogen gas.
b.
A glowing splint relights in a test tube of oxygen gas.
c.
Carbon dioxide turns limewater (calcium hydroxide solution) cloudy white.
d.
Ammonia has a characteristic sharp, choking smell. It also makes damp red litmus
paper turn blue.
Ammonia forms a white smoke of ammonium chloride when hydrogen chloride gas,
from concentrated
hydrochloric acid, is held near it.
e.
Chlorine has a characteristic sharp, choking smell. It also makes damp blue
litmus paper turn red, and then
bleaches it white
Identification of ions
(Oxford AQA International GCSE Chemistry)
a.
Flame tests can be used to identify metal ions. Lithium, sodium, potassium,
calcium and barium
compounds produce distinctive colours in flame tests:
•
lithium compounds result in a crimson flame
•
sodium compounds result in a yellow flame
•
potassium compounds result in a lilac flame
•
calcium compounds result in a red flame
•
barium compounds result in a green flame.
Required practical:
Identify the metal ion in an unknown compound using flame testing techniques.
b.
Aluminium, calcium and magnesium ions form white precipitates with sodium
hydroxide solution but only
the aluminium hydroxide precipitate dissolves in excess sodium hydroxide
solution.
c.
Copper(II), iron(II) and iron(III) ions form coloured precipitates with sodium
hydroxide solution. Copper(II)
forms a blue precipitate, iron(II) a green precipitate and iron(III) a brown
precipitate.
d.
Carbonates react with dilute acids to form carbon dioxide. Carbon dioxide
produces a white precipitate
with limewater, which turns limewater cloudy white.
e.
Halide ions in solution produce precipitates with silver nitrate solution in the
presence of dilute nitric acid.
Silver chloride is white, silver bromide is cream and silver iodide is yellow.
f.
Sulfate ions in solution produce a white precipitate with barium chloride
solution in the presence of dilute
hydrochloric acid.
ACIDS, BASES AND SALTS
(Oxford AQA International GCSE Chemistry)
This section looks in greater detail at the properties and applications of acids
and bases.
The properties of acids and bases
(Oxford AQA International GCSE Chemistry)
a.
Metal oxides and hydroxides are bases. Soluble hydroxides are called alkalis.
b.
Acids react with bases to form salts. These reactions are called neutralisation
reactions.
c.
The particular salt produced in any reaction between an acid and a base or
alkali depends on:
•
the acid used (hydrochloric acid produces chlorides, nitric acid produces
nitrates, sulfuric acid
produces sulfates)
•
the metal in the base or alkali.
d.
Ammonia dissolves in water to produce an alkaline solution. It is used to
produce ammonium salts.
e.
A solution of calcium hydroxide in water (limewater) reacts with carbon dioxide
to produce calcium
carbonate.
f.
Hydrogen ions, H
+
(aq), make solutions acidic and hydroxide ions, OH–
(aq), make solutions alkaline. The pH
scale is a measure of the acidity or alkalinity of a solution.
Students should be familiar with the pH scale from 0 to 14, and know that pH 7
is a neutral solution.
Students should be able to describe the use of universal indicator to measure
the approximate pH of a
solution.
g.
In neutralisation reactions, hydrogen ions react with hydroxide ions to produce
water. This reaction can be
represented by the equation:
H+(aq) + OH–(aq)
→
H2O(l)
Preparation of salts
(Oxford AQA International GCSE Chemistry)
a.
Soluble salts can be made from acids by reacting them with:
•
metals – not all metals are suitable; some are too reactive and others are not
reactive enough
•
insoluble bases – the base is added to the acid until no more will react and the
excess solid is filtered off
•
alkalis – an indicator can be used to show when the acid and alkali have
completely reacted to produce a
salt solution.
Students should be able to suggest methods to make a named soluble salt.
b.
Salt solutions can be crystallised to produce solid salts.
c.
Insoluble salts can be made by mixing appropriate solutions of ions so that a
precipitate is formed.
Precipitation can be used to remove unwanted ions from solutions: for example,
in treating water for
drinking or in treating effluent.
Students should be able to name the substances needed to make a named insoluble
salt.
QUANTITATIVE CHEMISTRY
(Oxford AQA International GCSE Chemistry)
Conservation of mass is a key concept in chemistry and this is developed during
this section. This is then
used to develop a quantitative approach to chemical reactions, leading to many
opportunities to develop
experimental skills through practical work and mathematical skills
Conservation of mass including the quantitative interpretation of chemical
equations
a.
Chemical reactions can be represented by word equations or by symbol equations.
Students should be able to write word and balanced symbol equations for
reactions in the specification.
b.
Information about the states of reactants and products can be included in
chemical equations.
Students should be able to use the state symbols (g), (l), (s) and (aq) in
equations where appropriate.
c.
No atoms are lost or made during a chemical reaction so the mass of the products
equals the mass of the
reactants.
d.
The masses of reactants and products can be calculated from balanced symbol
equations.
Students should be able to calculate the mass of a reactant or product from
information about the masses
of the other reactants and products in the reaction and the balanced symbol
equation.
e.
Even though no atoms are gained or lost in a chemical reaction, it is not always
possible to obtain the
calculated amount of a product because:
•
the reaction may not go to completion because it is reversible
•
some of the product may be lost when it is separated from the reaction mixture
•
some of the reactants may react in ways different from the expected reaction.
Use of amount of substance in relation to masses of pure substances
a.
The relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms in the
numbers shown in the formula.
Students are expected to use relative atomic masses in the calculations
specified in the subject content.
Students should be able to calculate the relative formula mass (Mr)
of a compound from its formula.
b.
The percentage by mass of an element in a compound can be calculated from the
relative atomic mass of
the element in the formula and the relative formula mass of the compound.
c.
The empirical formula of a compound can be calculated from the masses or
percentages of the elements in
a compound.
Students should be able to calculate empirical formulae and molecular formulae.
The mole concept
(Oxford AQA International GCSE Chemistry)
a.
The relative formula mass of a substance, in grams, is known as one mole of that
substance.
Students should be able to use the relative formula mass of a substance to
calculate the number of moles
in a given mass of that substance and vice versa.
b.
One mole contains 6.02 × 1023
atoms or molecules. This number is known as Avogadro’s constant.
Using molar concentrations of solutions
(Oxford AQA International GCSE Chemistry)
a.
The concentration of a solution is related to the mass of the solute (in terms
of number of moles) and the
volume of the solution. The concentration of a solution is calculated as
follows:
Concentration (mol/dm3) = number of moles/volume of solution (in dm3).
b.
The volumes of acid and alkali solutions that react with each other can be
measured by titration using a
suitable indicator.
Students should be able to carry out titrations using strong acids and strong
alkalis only (sulfuric,
hydrochloric and nitric acids only).
Required practical:
Establish the concentration of an unknown strong acid through titration with a
strong base.
c.
If the concentration of one of the reactants is known, the results of a
titration can be used to find the
concentration of the other reactant.
Students should know how to carry out a titration and be able to calculate the
chemical quantities in
titrations involving concentrations in mol/dm3
and in g/dm3.
d.
The molar gas volume at room temperature and pressure is assumed to be 24 dm3
Students are expected to be able to calculate the number of moles or the volume
of gas in a reaction
TRENDS WITHIN THE PERIODIC TABLE
(Oxford AQA International GCSE Chemistry)
This section looks to both describe and explain trends within the periodic table
along with more detailed
knowledge and understanding of identified groups.
Group properties
(Oxford AQA International GCSE Chemistry)
a.
The elements in Group 1 of the periodic table (known as the alkali metals):
•
are metals with low density (the first three elements in the group are less
dense than water)
•
react with non-metals to form ionic compounds in which the metal ion carries a
charge of +1. The
compounds are white solids that dissolve in water to form colourless solutions
•
react with water, releasing hydrogen
•
form hydroxides that dissolve in water to give alkaline solutions.
b.
In Group 1, the further down the group an element is, the more reactive the
element.
c.
The elements in Group 7 of the periodic table (known as the halogens) react with
metals to form ionic
compounds in which the halide ion carries a charge of –1.
d.
In Group 7, the further down the group an element is:
•
the less reactive the element
•
the higher its melting point and boiling point.
e.
A more reactive halogen can displace a less reactive halogen from an aqueous
solution of its salt.
f.
The trends in reactivity within groups in the periodic table can be explained
because the higher the energy
level of the outer electrons:
•
the more easily electrons are lost
•
the less easily electrons are gained.
Students should be able to explain the relative reactivities of the elements in
Group 1 and 7
TRANSITION METALS
(Oxford AQA International GCSE Chemistry)
a.
Transition metals are those in the centre of the periodic table between Groups 2
and 3. Many transition
metals have ions with different charges, form coloured compounds and are useful
as catalysts.
b.
Compared with the elements in Group 1, transition metals:
•
have higher melting points (except for mercury) and higher densities
•
are stronger and harder
•
are much less reactive and so do not react as vigorously with water or oxygen
THE RATE OF CHEMICAL CHANGE
(Oxford AQA International GCSE Chemistry)
Rate of reaction
(Oxford AQA International GCSE Chemistry)
a.
The rate of a chemical reaction can be found by measuring the amount of a
reactant used or the amount of
product formed over time:
Rate of reaction =
amount of reactant used /
time
Rate of reaction =
amount of product formed /
time
Students need to be able to interpret graphs showing the amount of product
formed (or reactant used up)
with time, in terms of the rate of the reaction.
Knowledge of specific reactions other than those in the subject content is
not
required, but students will
be expected to have studied examples of chemical reactions and processes in
developing their skills during
their study of this section.
b.
Chemical reactions can occur only when reacting particles collide with each
other and with sufficient
energy. The minimum amount of energy that particles must have to react is called
the activation energy.
c.
Increasing the temperature increases the speed of the reacting particles so that
they collide more
frequently and more energetically. This increases the rate of reaction.
d.
Increasing the pressure of reacting gases increases the frequency of collisions
and so increases the rate of
reaction.
e.
Increasing the concentration of reactants in solutions increases the frequency
of collisions and so increases
the rate of reaction.
f.
Increasing the surface area of solid reactants increases the frequency of
collisions and so increases the rate
of reaction.
Required practical:
Investigate factors affecting the rate of a reaction.
g.
Catalysts change the rate of chemical reactions but are not used up during the
reaction. Different reactions
need different catalysts.
Knowledge of named catalysts other than those specified in the subject content
is
not
required, but
students should be aware of some examples of chemical reactions and processes
that use catalysts.
h.
Catalysts are important in increasing the rates of chemical reactions used in
industrial processes to reduce
costs
FACTORS AFFECTING EQUILIBRIUM
(Oxford AQA International GCSE Chemistry)
a.
When a reversible reaction occurs in a closed system, equilibrium is reached
when the reactions occur at
exactly the same rate in each direction.
b.
The relative amounts of all the reacting substances at equilibrium depend on the
conditions of the reaction.
c.
If the temperature is raised:
•
the yield from the endothermic reaction increases
•
the yield from the exothermic reaction decreases.
If the temperature is lowered:
•
the yield from the endothermic reaction decreases
•
the yield from the exothermic reaction increases.
d.
In gaseous reactions:
•
an increase in pressure will favour the reaction that produces the least number
of molecules as shown
by the symbol equation for that reaction
•
a decrease in pressure will favour the reaction that produces the greatest
number of molecules as
shown by the symbol equation for that reaction.
e.
These factors, together with reaction rates, are important when determining the
optimum conditions in
industrial processes, including the Haber process.
PRODUCTION OF AMMONIA AND SULFURIC ACID
(Oxford AQA International GCSE Chemistry)
a.
The raw materials for the Haber process are nitrogen and hydrogen. Nitrogen is
obtained from the air and
hydrogen may be obtained from natural gas or other sources.
b.
Ammonia is a raw material in the production of fertilizers.
Students should be able to explain the global need for fertilizers to maximise
food yields.
c.
The purified gases are passed over a catalyst of iron at a high temperature
(about 450°C)
and a high
pressure (about 200 atmospheres). Some of the hydrogen and nitrogen react to
form ammonia. The
reaction is reversible so ammonia breaks down again into nitrogen and hydrogen:
nitrogen + hydrogen
?
ammonia
On cooling, the ammonia liquefies and is removed. The remaining hydrogen and
nitrogen are recycled.
d.
Sulfuric acid is produced industrially using the contact process. It is a
three–stage process, which
incorporates a reversible process and the use of a catalyst.
Stage 1: Sulfur is burned in air to produce sulfur dioxide
S(s) + O2(g)
→
SO2(g)
Stage 2: Sulfur dioxide reacts with more oxygen to make sulfur trioxide
2SO2(g)
+ O2(g)
2SO3(g)
This exothermic reaction is reversible and it requires a catalyst of Vanadium(V)
oxide, V2O5,
a temperature
of around 450
°C and atmospheric pressure
Stage 3: Sulfur trioxide reacts with water to make sulfuric acid
H2O(l)
+ SO3(g)
→
H2SO4(l
or aq)
Students should be able to describe the stages in the contact process and also
to explain why a catalyst, a
high temperature and atmospheric pressure are used in Stage 2
REDOX REACTIONS
(Oxford AQA International GCSE Chemistry)
a.
Oxidation can be described as the gain of oxygen by a substance and reduction as
the loss of oxygen from
a substance.
b.
Oxidation can also be described as the loss of electrons and reduction as gain
of electrons.
Students should be able to describe chemical reactions within this specification
in terms of oxidation and
reduction using the definitions above.
c.
When oxidation and reduction are happening at the same time this is known as a
redox reaction, for
example.
Fe2O3
+ 3CO
==> 2Fe + 3CO2
Iron(III) oxide is reduced (oxygen loss) and the carbon monoxide is oxidised
(oxygen gain).
ENERGY CHANGES
(Oxford AQA International GCSE Chemistry)
This section highlights that chemical reactions involve changes which require
energy to make them happen.
This is a fundamental concept which links to key ideas in biology and physics.
The section also involves
developing mathematical skills and also application of knowledge
Exothermic and endothermic reactions
(Oxford AQA International GCSE Chemistry)
a.
When chemical reactions occur, energy is transferred to or from the
surroundings.
Knowledge of delta H (ΔH) conventions and enthalpy changes, including the use of
positive values for
endothermic reactions and negative values for exothermic reactions, is required.
b.
An exothermic reaction is one that transfers energy to the surroundings.
Examples of exothermic reactions
include combustion, many oxidation reactions and neutralisation.
Students should be able to give examples of exothermic reactions including
combustion, oxidation and
neutralisation. Everyday uses of exothermic reactions include self-heating cans
(eg for coffee) and hand
warmers.
c.
An endothermic reaction is one that takes in energy from the surroundings.
Endothermic reactions include
thermal decompositions. Some sports injury packs are based upon endothermic
reactions.
d.
In some chemical reactions, the products of the reaction can react to produce
the original reactants. Such
reactions are called reversible reactions and are represented as follows:
If
A + B
==>
C + D is exothermic, then C + D ==> A + B is endothermic
For example:
blue
hydrated
copper
sulfate
== heat ==> white anhydrous copper sulfate + water (endothermic)
white
anhydrous
copper
sulfate
+ water ==> blue hydrated copper sulfate (exothermic, mixture heats up)
Calculating and explaining energy change
(Oxford AQA International GCSE Chemistry)
a.
The relative amounts of energy released when substances burn can be measured by
simple calorimetry, eg
by heating water in a glass or metal container. This method can be used to
compare the amount of energy
produced by fuels.
Students should be able to calculate and compare the amount of energy released
by different fuels given
the equation:
Q =
mc ΔT
b.
Energy is normally measured in joules (J) or kilojoules (kJ) for a given mass or
amount of substance eg
kilojoules per gram or kilojoules per mole.
c. The amount of energy produced by a chemical reaction in solution can be
calculated from the measured
temperature change of the solution when the reagents are mixed in an insulated
container. This method
can be used for reactions of solids with water or for neutralisation reactions.
d.
Simple energy level diagrams can be used to show the relative energies of
reactants and products, the
activation energy and the overall energy change of a reaction.
Students will be expected to understand simple energy level diagrams showing the
relative energies of
reactants and products, the activation energy and the overall energy change,
with a curved arrow to show
the energy as the reaction proceeds.
Students should be able to relate these to exothermic and endothermic reactions.
e.
During a chemical reaction:
•
energy must be supplied to break bonds
•
energy is released when bonds are formed.
Students should be able to calculate the energy transferred in reactions and
interpret simple energy level
diagrams in terms of bond breaking and bond formation (including the idea of
activation energy and the
effect on this of catalysts).
f.
In an exothermic reaction, the energy released from forming new bonds is greater
than the energy needed
to break existing bonds.
Students should be able to calculate the energy transferred in reactions using
bond dissociation energies
supplied.
g.
In an endothermic reaction, the energy needed to break existing bonds is greater
than the energy released
from forming new bonds.
h.
Catalysts provide a different pathway for a chemical reaction that has a lower
activation energy.
Students should be able to represent the effect of a catalyst on an energy level
diagram
CHEMICAL CELLS AND FUEL CELLS
(Oxford AQA International GCSE Chemistry)
a.
A chemical cell produces a potential difference until the reactants are used up.
b.
Fuel cells produce electricity through the reaction of a fuel with oxygen.
Hydrogen-oxygen fuel cells
use hydrogen as their fuel, and are useful in cars and spacecraft. Water is the
only waste product from a
hydrogen–oxygen fuel cell, so they cause less pollution when in use.
Students should be able to compare the advantages and disadvantages of the
combustion of hydrogen
with the use of hydrogen fuel cells from information that is provided.
Students should know and understand the benefits and disadvantages of hydrogen
fuel in terms of:
•
storage and use
•
products of combustion.
Knowledge of the details of the reactions in fuel cells is
not
required.
ORGANIC CHEMISTRY
(Oxford AQA International GCSE Chemistry)
Carbon compounds as
fuels
(Oxford AQA International GCSE Chemistry)
Crude oil
(Oxford AQA International GCSE Chemistry)
a.
Crude oil is a mixture of a very large number of compounds.
b.
Most of the compounds in crude oil are hydrocarbons, which are molecules made up
of hydrogen and
carbon atoms only.
c.
The many hydrocarbons in crude oil may be separated into fractions, each of
which contains molecules
with a similar number of carbon atoms, by evaporating the oil and allowing it to
condense at a number of
different temperatures. This process is called fractional distillation.
Students should know and understand the main processes in continuous fractional
distillation in a
fractionating column.
Knowledge of the names of specific fractions or fuels is
not
required
Hydrocarbons
(Oxford AQA International GCSE Chemistry)
a.
Most of the hydrocarbons in crude oil are saturated hydrocarbons called alkanes.
The general formula for
the homologous series of alkanes is CnH2n+2
Students should know that in saturated hydrocarbons all the carbon–carbon bonds
are single covalent
bonds.
b.
Alkane molecules can be represented in the following forms:
C2H6
or

Students should know that in displayed structures
represents a covalent bond.
Students should be able to recognise alkanes from their formulae in any of the
forms, but do not need to
know the names of specific alkanes other than methane, ethane and propane.
c.
Some properties of hydrocarbons depend on the size of their molecules. These
properties influence how
hydrocarbons are used as fuels.
Knowledge and understanding of trends in properties of hydrocarbons is limited
to:
•
boiling points,
viscosity and
flammability.
d.
Most fuels, including coal, contain carbon and/or hydrogen and may also contain
some sulfur. The gases
released into the atmosphere when a fuel burns may include carbon dioxide, water
(vapour), carbon
monoxide, sulfur dioxide and oxides of nitrogen. Solid particles (particulates)
may also be released. Solid
particles may contain soot (carbon) and unburnt fuels.
Sulfur dioxide and oxides of nitrogen cause acid rain, an increase in carbon
dioxide may result in climate
change, and solid particles cause global dimming
Students should be able to relate products of combustion to the elements present
in compounds in the fuel
and to the extent of combustion (whether complete or incomplete).
No details of how the oxides of nitrogen are formed are required, other than the
fact that they are formed
at high temperatures.
e.
The combustion of hydrocarbon fuels releases energy. During combustion, the
carbon and hydrogen in the
fuels are oxidised.
f.
Ethanol can be made by reacting ethene with steam:
C2H4
+ H2O
→
C2H5OH
Phosphoric acid is used as a catalyst to increase the rate of the reaction.
This is efficient because it is a continuous process. However, ethene is derived
from crude oil, a non-renewable
resource which may run out one day.
Ethanol can also be made by fermenting sugar:
C6H12O6
→
2C2H5OH
+ 2CO2
Enzymes in yeast are natural catalysts for this reaction, and this is a batch
process. Unlike ethene, sugar is a
renewable resource.
Students should be able to compare the two ways of making ethanol in terms of
type of raw material, type
of process, labour, rate of reaction, conditions needed, purity of product and
energy requirements
g.
Biofuels, including biodiesel and ethanol, are produced from plant material, and
are possible alternatives to
hydrocarbon fuels.
Students should know and understand the benefits and disadvantages of biofuels
in terms of:
•
use of renewable resources
•
their impacts on land use
•
their carbon footprint.
Students should know that ethanol for use as a biofuel is produced from a dilute
solution of ethanol
obtained by the fermentation of plant materials at a temperature between 20 °C
and 35 °C. Detailed
knowledge of the methods used to produce other biofuels is
not
required.
Obtaining useful substances from crude oil
(Oxford AQA International GCSE Chemistry)
a.
Hydrocarbons can be broken down (cracked) to produce smaller, more useful
molecules. This process
involves heating the hydrocarbons to vaporise them. The vapours are either
passed over a hot catalyst or
mixed with steam and heated to a very high temperature so that thermal
decomposition reactions then
occur.
b.
The products of cracking include alkanes and unsaturated hydrocarbons called
alkenes. The general formula
for the homologous series of alkenes is CnH2n
Students should know that in unsaturated hydrocarbons some of the carbon–carbon
bonds are double
covalent bonds.
Required
practical:
Test for the presence of a double bond in an unknown hydrocarbon.
c.
Unsaturated hydrocarbon molecules can be represented in the following forms:
C3H6
or
Students should know that in displayed structures
represents a double bond.
Students should be able to recognise alkenes from their names or formulae, but
do
not
need to know the
names of individual alkenes other than ethene and propene.
d.
Alkenes react with bromine water, turning it from orange to colourless.
e.
Some of the products of cracking are useful as fuels
Synthetic and naturally occurring polymers
(Oxford AQA International GCSE Chemistry)
a.
Alkenes can be used to make polymers such as poly(ethene) and poly(propene). In
polymerisation
reactions, many small molecules (monomers) join together to form very large
molecules (polymers).
For example - the formation of the polymer poly(ethene) from the monomer ethene
Students should be able to recognise the molecules involved in these reactions
in the forms shown in
the subject content. They should be able to represent the formation of a polymer
from a given alkene
monomer.
Further details of polymerisation are
not
required.
b.
The properties of polymers depend on what they are made from and the conditions
under which they are
made. For example, low-density (LD) and high-density (HD) poly(ethene) are
produced using different
catalysts and reaction conditions.
c.
Thermosoftening polymers consist of individual, tangled polymer chains.
Thermosetting polymers consist
of polymer chains with cross-links between them so that they do not melt when
they are heated.
Extension Tier students should be able to explain thermosoftening polymers in
terms of intermolecular
forces.
d.
Polymers have many useful applications and new uses are being developed.
Examples include: new
packaging materials, waterproof coatings for fabrics, dental polymers, wound
dressings, hydrogels, and
smart materials (including shape memory polymers).
Students should consider the ways in which new materials are being developed and
used, but will not need
to recall the names of specific examples.
e.
Many polymers are not biodegradable, ie they are not broken down by microbes.
This can lead to problems
with waste disposal.
Knowledge of specific named examples is
not
required, but students should be aware of the problems that
are caused in landfill sites and in litter.
f.
Plastic bags are being made from polymers and cornstarch so that they break down
more easily.
Biodegradable plastics made from cornstarch have been developed
Organic compounds – their structure and reactions
Alcohols
a.
Alcohols contain the functional group –OH. Methanol, ethanol and propanol are
the first three members of
a homologous series of alcohols. Alcohols can be represented in the following
forms:
CH3CH2OH or
Students should be able to recognise alcohols from their names or formulae, but
do
not
need to know the
names of individual alcohols other than methanol, ethanol and propanol.
b.
Methanol, ethanol and propanol:
•
dissolve in water to form a neutral solution
•
react with sodium to produce hydrogen
•
burn in air
•
are used as fuels and solvents, and ethanol is the main alcohol in alcoholic
drinks.
c.
Ethanol can be oxidised to ethanoic acid, (a carboxylic acid) either by chemical
oxidising agents or by
microbial action. Ethanoic acid is the main acid in vinegar.
Carboxylic acids
a.
Ethanoic acid is a member of the homologous series of carboxylic acids, which
have the functional group
–COOH. The structures of carboxylic acids can be represented in the following
forms:
CH3COOH or
Students should be able to recognise carboxylic acids from their names or
formulae, but do
not
need to
know the names of individual carboxylic acids other than methanoic acid,
ethanoic acid and propanoic acid.
b.
Carboxylic acids:
•
dissolve in water to produce acidic solutions
•
react with carbonates to produce carbon dioxide
•
react with alcohols in the presence of an acid catalyst to produce esters
•
do not ionise completely when dissolved in water and so are weak acids
•
aqueous solutions of weak acids have a higher pH value than aqueous solutions of
strong acids with the
same concentration.
Students are expected to write balanced chemical equations for the reactions of
carboxylic acids
Esters
a.
Esters have the functional group –COO–. The structures of esters can be
represented in the following
forms:
CH3COOCH2CH3
or
Students will
not
be expected to give the names of esters other than ethyl ethanoate, but should
be able to
recognise a compound as an ester from its name or its structural formula.
Ethyl ethanoate is the ester produced from ethanol and ethanoic acid (its a
reversible reaction).
ethanoic acid + ethanol
ethyl ethanoate + water
+
+ H2O
sometimes more simply written as
CH3COOH + CH3CH2OH
CH3COOCH2CH3 + H2O
b.
Esters are volatile compounds with distinctive smells and are used as
flavourings and perfumes
The exam PERIODIC TABLE
(Oxford AQA International GCSE Chemistry)
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