Question

1.      Subshells half-filled with electrons are particularly stable. Can you suggest a possible

physical basis for this claim?

Answer 1

Possible basis for this claim:

1) (Simple exmplanation) Electrons experience forces of repulsion from other electrons so they don't exactly enjoy inhabiting the same orbital. When electrons half-fill a subshell they essentially get the maximum amount of space for movement and this leads to stability.

2) (A more complex explanation) Half-filled subshell are stable due to symmetrical electron distribution. The energetic benefit of having multiple electrons with the same energy and same spin is called 'exchange energy'. In half-filled subshells all of the electrons are equivalent and can exchange with each other and exchange energy is great. This makes half-filled subshells particularly stable.