Describe on Hund’s Principle

Hund’s Principle: According to this rule, electron pairing will not take place in orbital of same energy (same subshell) until each orbital is singly tilled.

According to Hund’s principle, electronic principle O₂ and P are shown below:

Oxygen (8): 1s² 2s² 2px² 3py¹ 4pz¹

Phosphorous (15): 1s² 2s² 2px² 2py² 2pz² 3s² 3px¹ 3py¹ 3pz¹