Question

Halogen having greatest electron affinity

• A. F
• B. Cl
• C. Br
• D. I

Answer 1

Answer: (B)

Electron affinity (EA) is the amount of energy associated with the gain of electrons by the gaseous atom.
$A(g)+e^{-}⟶A^{-}(g)EA=-xkJmo{l}^{-1}$
In a group from top to bottom EA generally decreases. It decreases with increases in atomic size.
In the halogens the electron affinity of chlorine is maximum and decreases from chlorine to iodine. The order of EA of halogens is
$Cl>F>Br>I$
The EA of fluorine is smaller than that of chlorine. It is due to small atom size of fluorine. Therefore, there is repulsion between the added electron and the valence electron.