Question

Which of the following orders is incorrect about electron affinity?

• A. $P>N$
• B. $B>N$
• C. $O>Se$
• D. $Cl>I$

Answer 1

The correct option is C $O>Se$

Electron affinity is the amount of energy released when an electron is added to a neutral atom to form an anion.

A) It generally increases across the period due to the increasing effective nuclear charge. However due to small size, N has lesser electron affinity than P. $\therefore P>N$

B) $N$ has a half filled stable configuration. So, it will be reluctant towards accepting an electron. $\therefore B>N$

C) Generally, down the group EA decreases. But here, $Se>O$ because in group 16, $O$ has minimum electronic affinity. This is because of small size and interclectronic repulsions in $O$.

D) Electron affinity decreases down the group due to increase in the number of shells. $\therefore Cl>I$