Question
How does electron gain enthalpy vary along a group?
Solution
The electron gain enthalpy of elements become less negative as we move from top to bottom down a group. This is because on moving down a group, there is the simultaneous increase in atomic size and nuclear charge. However, the effect of the increase in size is greater than the increase in nuclear charge. As a result, the incoming electron feels lesser attraction by the large atom. Consequently, electron gain enthalpy becomes less negative down a group.
