Question

The subshell electronic configuration of an element is given in 2 ways
a) 1s2 2s2 2p6 3s2 3p6 3d4 4s2
b) 1s2 2s2 2p6 3s2 3p6 3d5 4s1
which one is correct? Give reasons​

Answer 1

Answer:

Option b is correct because it has a stable electronic configuration due to the half-filled orbitals.

Explanation:

The atom is more stable than other electronic configurations due to half-filled or fully filled orbitals. Symmetry and exchange energy are the reasons for the greater stability of atoms with half-filled or fully filled orbitals.

(1)$1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{5} 4s^{1}$ - here the d and s orbitals are half-filled.

(2)$1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{4} 4s^{2}$ -  here there are no half-filled orbitals.

Therefore (1) is the stable electronic configuration.