How many unpaired electrons are there in a complex ion having a d⁵ electron configuration and an octahedral geometry in the weak field case? A)1 B)2 C)3 D)4 E)5

Question

Quizplus · Accepted Answer

In a weak field octahedral complex, the electrons will fill the lower energy $t_{2g}$ orbitals first, but due to the weak field, they will also occupy the higher energy $e_g$ orbitals before pairing up in the $t_{2g}$ orbitals. The given electron configuration $d^5$ indicates there are 5 d-electrons to distribute. In a weak field scenario, these electrons will fill each of the five d-orbitals (three $t_{2g}$ and two $e_g$) singly first, resulting in five unpaired electrons.

How Many Unpaired Electrons Are There in a Complex Ion