Question

The electron affinity values for the halogens show the following trend ...

• A. F < Cl > Br > I
• B. F < Cl < Br < I
• C. F > Cl > Br > I
• D. F < Cl > Br < I

Answer 1

The correct option is A F < Cl > Br > I

In a group of non-metals, electron gain enthalpy of the $2^{nd}$ element is maximum. Among halogens, chlorine has the highest election affinity.
We would expect fluorine would have the highest electron affinity because of being a halogen and very small size, but its so small that it leads to interelectronic repulsions and the overall energy released when an electron is added is reduced.