Question

Why are half-filled d-orbitals more stable?

Answer 1

The half-filled subshells are stable due to the following reasons:

• Symmetrical distribution of electrons: The symmetrical distribution of electrons in the partially filled or fully filled subshells makes them more stable. Electrons in the same subshell have different spatial distributions but have equal energy. Consequently, their shielding of one another is relatively small and the electrons are more strongly attracted by the nucleus.
• Exchange Energy: When two or more electrons with the same spin are present in the degenerate orbitals of a subshell. These electrons frequently swap positions and the energy produced as a result is known as exchange energy. The highest number of exchanges is possible when the subshell is either half-filled or fully filled. As a result, both the stability and the exchange energy are at their maximum.
• A possible exchange for a ${\mathrm{d}}^5$ configuration is as follows:-
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