Q. The electronic configurations of four elements are given below. Arrange these elements in the correct order of the magnitude (without sign) of their electron affinity. $2s^{2}2p^{5}$ $3s^{2}3p^{5}$ $2s^{2}2p^{4}$ $3s^{2}3p^{4}$ Select the correct answer using the codes given below
A) (i) < (ii)<(iv)<(iii)
B) (ii)<(i)<(iv)<(iii)
C) (i)<(iii)<(iv)<(ii)
D) (iii)<(iv)<(i)<(ii)
Explanation
(d)
Electron affinity is defined as “the energy released when an extra electron is added to neutral gaseous atom. The increasing order of electron affinity is
$2s^{2}2p^{4} < 3s^{2}3p^{4} < 2s^{2}2p^{5} < 3s^{2}3p^{5}$
$O < S < F < Cl$
General electron affinity decreases with the increase in the size of atom, since nuclear attraction decrease down a group. The value of electron affinity increase as we move along a period since the size of atoms decrease in a period. Electron affinity of O and F are less than S and Cl respectively due to very small size.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.