Question

Fluorine has the highest electronegativity among the $n{s}^{2}n{p}^5$ group on the Pauling scale, but the electron affinity of fluorine is less than that of chlorine because:

• A. the atomic number of fluorine is less than that of chlorine.
• B. fluorine being the first member of the family behaves in an unusual manner.
• C. chlorine can accommodate an electron better than fluorine by utilising its vacant 3d-orbital.
• D. small size, high electron density and an increased electron repulsion makes addition of an electron to fluorine less favourable than that in the case of chlorine.

Answer 1

The correct option is C chlorine can accommodate an electron better than fluorine by utilising its vacant 3d-orbital.

A valence-electron in a multi-electron atom is attracted by the nucleus and repelled by the electrons of inner-shells. The combined effect of this attractive and repulsive force acting on the valence-electron experiences less attraction from the nucleus. This is called shielding or screening effect.

In Cl, there are empty d-orbitals where it can accommodate its electron and because of this, attraction forces increases and electron affinity also.

So, the correct option is $C$