Chemists can use the theory of structure
and bonding to explain the physical and chemical properties of materials of
widely varying composition e.g. salt crystals, metals and polymer plastics.
Detailed analysis of structures by a variety of techniques shows how
atoms can be arranged in all sorts of ways summarised below with links to
more detailed notes.
Chemical bonding theory (covalent, ionic, metallic) explains how atoms are held together in
these different types of structure.
This theoretical chemical bonding knowledge,
backed up with experimental evidence, helps
scientists to design and engineer new materials with desirable properties
for specific uses.
Composites, smart materials and
nanotechnology have provided materials with a huge diverse and
remarkable sets of properties for many applications.
The properties of these new materials offer new
technological applications and uses in a range of different industrial and
domestic use of technologies from electronic
devices to new structural materials and a lot more besides.
Biochemistry has advanced enormously from the mid 20th century onwards
including the deducing the structure of DNA and understanding how
genetics work (well mostly!).
Drugs save lives every day or just
relieve that annoying headache.
An understanding of the shape and
function of enzymes has enabled biochemists to use computer software to
design drugs to combat disease.
Artists
have taken advantage of new alloys to create great sculptures like the
steel "Angel of the North" in north-east England..
Organic chemistry has outstripped any
other branch of chemistry and there are more compounds of carbon than any
other element in the Periodic Table (many millions of compounds including fuels, plastics,
pharmaceutical products etc. etc.!).
Three types of strong
chemical bonds: ionic, covalent and metallic will be described and explained.
In ionic bonding the particles
(atoms or a group of atoms) form oppositely charged ions.
Ionic bonding occurs in compounds formed from metals
combined with non-metals.
In covalent
bonding the particles are atoms (usually both non-metals) share pairs of
electrons to form the bond.
Covalent bonding occurs in most non-metallic
elements and in compounds of non-metals.
In metallic bonding the metal atoms (actually
positive ions) of the lattice share negative delocalised electrons to bind
themselves together.
Metallic bonding occurs in metallic
elements and alloys.
Overall you should be able to explain chemical bonding in terms
of electrostatic forces and the transfer or sharing of electrons and use the
bonding models to explain the physical properties of elements and
compounds.
