Magnetic Quantum Number
The quantum number mₗ that specifies the spatial orientation of an orbital relative to an applied magnetic field.
Formula / equation
mₗ = −l … 0 … +l
Unit
Dimensionless
In depth
The 2l + 1 permitted values explain why a p subshell has three orbitals and a d subshell five. These orbitals are degenerate in a free atom but split in energy under a magnetic field, producing the Zeeman effect, and split under a ligand field to give the colours of transition-metal complexes.
Examples in the real world
For l = 1 the values −1, 0 and +1 correspond to the pₓ, p_y and p_z orbitals.