The periodic table

The periodic table

Each horizontal row is a period

Each vertical row is a group

Elements are arranged in order of increasing atomic number

The trend in properties that is repeated across each period is call periodicity

Atoms of elements in the same group react similarly because they have the same number of e- in their outer shell and the same type of orbitals

Ionisation energies and atomic radii

Across a period, number of protons increases and e- are added to the same shell, so there is greater attraction between outer e- and nucleus, so atomic radius decreases and ionisation energy increases

At the start of a new period, there is a significant decrease in ionisation energy, this is due to the addition of a new shell

Down a group, the number of inner shells increases, so there is less attraction between outer e- and nucleus due to increased electron sheilding and increased distance from positive nucleus, so atomic radius increases and ionisation energy decreases. 

It is important to note, that whilst the number of protons increases down a group, its effects are outweighed by the significant increase in e- repulsion and atomic radius

Boiling points

Giant metallic structures have high boiling points. This is due to strong forces between the positive ions and negative delocalised e-.

Giant covalent structures have high boiling points. This is due to the strong forces between the atoms.

Simple molecular structures have low boiling points. This is due to the weak VDWs forces between the molecules.

We can see this pattern in boiling points across a period as we go from…