Magnetism due to unfilled atomic shells

Magnetism in isolated atoms and ions can be due to the electrons of unfilled atomic shells. Although nuclei have a magnetic moment, it is usually ignored because it is much smaller than the magnetic moments of the electrons in the unfilled shells. In an isolated atom, the total magnetic moment for the atom is the sum of the moments of each electron. That can be found by summing the magnetic moment of the orbital ML and the moment of the electron spin Ms. These two moments will vanish for filled shells, so only the unfilled shells moment is count in the total magnetic moment.