Thu July 19, 2012 By: Sivendu Sivendu

Fluorine is more electronegative than chlorine but electron affinity of fluorine is less than chlorine.why? Explain in detail.

Expert Reply
Thu July 19, 2012
The electron affinity of an element is the energy given off when a neutral atom in the gas phase gains an extra electron to form a negatively charged ion. A fluorine atom in the gas phase, for example, gives off energy when it gains an electron to form a fluoride ion.

F(g) + e- -----> F-(g) deltaHo = -328.0 kJ/mol 
The electron cloud of F is more dense than that of Cl because Cl is larger in size. So electrons can't enter in Florine's valence shell because of electrostatic force of rapultion of electro &electron cloud. So, electron affinity of fluorine is comparatively less than chlorine.
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