Question

Which of the following property decreases down a group :
(a) Ionization enthalpy (b) Atomic radii (c) Valency (d) All the above
properties

Answer 1

Atomic radius increases down the group. Hence nuclear attraction for the valence electron decreases down the group. So less energy will be required to remove such an electron. Hence ionisation enthalpy DECREASES DOWN THE GROUP.

Answer 2

ionization enthalpy decreases down a group