Hund's Rules
1.The state with the largest value of S is the most stable, and stability de ceases with decreasing S.
2. For states with the same value of S, the state with the largest valuc of L is the most stable.
3. If the states have the same values of L and S, then, for a subshell that is less than half-filled, the state with the smallest value of J is the
most stable; for a subshell that more than half-filled, the state with the largest value of J is the most stable.