Revision Slides for AQA A-Level Chemistry on Periodicity. Designed for the new Exam Series of June 2017 but can be used for earlier series.

1. Periodicity
Revision Slides

2. Atomic Radii
Moving across the table, atomic radius decreases. This
is because there is an increased nuclear charge, due
to an increase in the amount of protons, but equal
shielding and thus more attraction. This means the
electron shells are pulled further in to the atom and
the radius is decreased.

3. Ionisation Energies
The general trend moving across the table is
for ionisation energy to increase. It
decreases with group 3 and group six,
however. This is because, with group 3, the
single electron in the p-shell is in a higher
energy level and so requires less energy to
be taken away from the atom. Group 6 also
does this as in the p-shell, also, two
electrons are paired in an orbital and repel,
already providing some of the energy
required to pull the electron away. Also, in
spotting which group an unknown entity
belongs to, look at the last regular value
before the big jump in a successive
ionisation energy.

4. Melting and Boiling Points
The noble gas, group 8, elements have
remarkably low MPTs and BPTs due to
only weak van der Waals forces. As
they are only molecular, having
reasonably weak van der Waals forces
between them, groups 7, 6 and 5 have
also low MPTs and BPTs. Their
macromolecular structure and
intramolecular covalent forces give
group 4 elements the highest values.
Groups 1 and 2 have relatively high
values as they are metallic, with group
3 even higher.