Question

The correct order of electron affinity of oxygen, sulphur, chlorine, fluorine is

• A. $S<O<Cl<F$
• B. $S<O<F<Cl$
• C. $O<S<F<Cl$
• D. $O<S<Cl<F$

Answer 1

Answer: (C)

Electron affinity is the amount of energy liberated when one extra electron is added to an isolated gaseous atom. It usually increases along a period and decreases along a group. Thus, the order of electron affinity should be

$S<O<Cl<F$

But $F$ and $O$ due to their smaller size has lower electron affinity as compared to $Cl$ and $S$

respectively. Thus, the correct order of electron affinity is

$O<S<F<Cl$