quantum numbers
Solutions to Schrödingers equation involve four special numbers called quantum numbers . Three of the numbers, , , and , come from Schrödingers equation, and the fourth one comes from an extension of the theory . These four numbers completely describe the energy of an electron. Each electron has exactly four quantum numbers, and no two electrons have the same four numbers. The statement that no two electrons can have the same four quantum numbers is known as the Pauli exclusion principle .