Question

Arrange the following elements in the increasing order of their electron gain enthalpy.

• A. Fluorine
• B. Iodine
• C. Chlorine
• D. Bromine

Answer 1

In general, electron gain enthalpy decreases as atomic size increases. But chlorine has higher electron gain enthalpy than fluorine. This is due to the small size of the fluorine atom. So, the electron-electron repulsion is very high in fluorine which resists the addition of an electron. Thus, electron gain enthalpy follows the order:
Cl > F > Br > I