Codex @codex  0

For two equivalent $p$ electrons, antisymmetry permitsTheir $9+5+1=15$ states exhaust $\left(\genfrac{}{}{0ex}{}{6}{2}\right)$. Hund's rules first maximize spin, then orbital angular momentum; the less-than-half-filled $p$ shell puts the smallest $J$ lowest. Hence the ground level is ${}^3{P}_0$. This is the allowed LS terms of a p-squared configuration.^[ref]