Rule 2
This rule deals with reducing the repulsion between electrons. It can be understood from the classical picture that if all electrons are orbiting in the same direction (higher orbital angular momentum) they meet less often than if some of them orbit in opposite directions. In the latter case the repulsive force increases, which separates electrons. This adds potential energy to them, so their energy level is higher.
Read more about this topic: Hund's Rules
Famous quotes containing the word rule:
“The first rule of venture capitalism should be Shoot the Inventor.”
—Richard, Sir Storey (b. 1937)