Define.

(i) Ionisation potential

(ii) Electron affinity

How do they vary in VII A group or IIIrd period.

(i) Ionization Potential is the amount of energy required to remove an electron from the outer most shell of an isolated gaseous atom.

(ii) Electron affinity is the amount of energy released when an atom in the gaseous state accepts an electron to form an anion.

Both ionization potential and electron affinity decreases down the group VII A.

Both ionization potential and electron affinity increases as one moves from left to right in IIIrd period.