Chapter 2, Problem 2.19P

Interpretation Introduction

Interpretation: The Coulombic energies and exchange energies for the following configuration of $d^4$ should be determined. Also, a state with lower energy should be determined.

  $\underset{\_}{\uparrow }\underset{\_}{\uparrow }\underset{\_}{\downarrow }\underset{\_}{\downarrow }\underset{\_}{}$

And,

  $\underset{\_}{\uparrow }\underset{\_}{\uparrow }\underset{\_}{\uparrow }\underset{\_}{\downarrow }\underset{\_}{}$

Concept introduction: When two negatively charged electrons occupy the same space in atom then they repel each other and this repulsion is measured as Coulombic energy of repulsion $\left({\Pi }_c\right)$ per pair of electron. Therefore, electron first singly occupied and then get paired in electronic configuration. Also, when two electrons with same energy exchange then they stabilize the configuration, this measured as exchange energy $\left({\Pi }_e\right)$ .