The Spin Quantum Number

The fourth quantum number, ms, determines the spin of an electron within an atomic orbital. 

The Fourth Quantum Number

Whereas the first 3 quantum numbers describe the atomic orbital where you find the electron, the final quantum number, ms, describes spin the electron possesses. 

Concept: Spin Quantum Number Part 1


The Pauli Exclusion Principle implies that two electrons in the same atomic orbital cannot spin in the same direction so as to avoid having the same four quantum numbers. 

Concept: Spin Quantum Number Part 2


Example: State the electron configuration of boron and list the four quantum numbers of the 1st and the 5th electron.