Chemistry Question on Classification

Question

Among $P, S, Cl, F$ , the elements with most negative and least negative electron gain enthalpy respectively, are

Answer 1

Solution

Generally, electron gain enthalpy increases as we move from left to right in a period and decreases as we go down in a group. But electron affinities of second period elements $(F, N)$ are less negative as compared to corresponding third period element. This is because of the small atomic size of second period elements. Hence, the correct order electron affinities is $P < S < F < Cl$ Least negative $(EA)$ Most negative $(EA)$