Section
7.12: Fourth Quantum Number or the Electron-Spin Magnetic Quantum Number (mS)
While
n, ℓ and mℓ characterize the orbital, the last quantum number
characterizes the direction in which the electron is spinning around its own
axis.
mS = + ½ electron is spinning
clockwise
mS = - ½ electron is spinning
counterclockwise
Two
electrons with the same ms values are said to have parallel spins. Two electrons with opposite ms
values are said to have anti-parallel spins, or opposite spins. The spin of an electron is often represented
by an arrow.
