Ionisation Enthalpy

Ionisation Enthalpy

Because the halogens sit only one electron short of a stable noble-gas configuration, they show very little inclination to give up an electron of their own — and this shows up as a very high ionisation enthalpy across the whole group. As with atomic radius, the trend down the group is governed by size: as the atom gets larger from F to I, its outermost electron sits farther from the nucleus an …