Question

chlorine has more negative electron gain enthalpy than fluorine why

Answer 1

The periodic trend for electron gain enthalpy is that it increases across the period and decreases down the group.But the exception is found in case of Cl and F.Cl has more electron gain enthalpy than fluorine as electron-electron repulsion is more pronounced in case of F due to smaller size so it avoids addition of one more electron in it. 

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