Explain Hund's rule of maximum multiplicity.

(N/A) Hund's rule of maximum multiplicity states that for a given electron configuration,the term with the maximum multiplicity has the lowest energy. In simpler terms,for orbitals of the same subshell ($p, d,$ or $f$),pairing of electrons does not occur until each orbital is singly occupied with electrons having parallel spins.
$1$. Electrons first occupy all empty orbitals of a subshell singly with parallel spins.
$2$. Pairing only begins once each orbital in the subshell contains one electron.
For example,in Nitrogen $(Z=7)$,the configuration is $1s^2 2s^2 2p_x^1 2p_y^1 2p_z^1$. In Oxygen $(Z=8)$,the configuration is $1s^2 2s^2 2p_x^2 2p_y^1 2p_z^1$.