For an electron in a 2s subshell, the allowed values of the magnetic quantum number mlm_lml are determined by the azimuthal quantum number lll.
- The principal quantum number n=2n=2n=2 for the 2s subshell.
- The azimuthal quantum number l=0l=0l=0 for an s subshell.
- The magnetic quantum number mlm_lml can take integer values from −l-l−l to +l+l+l, inclusive.
Since l=0l=0l=0 for the 2s subshell, the only allowed value for mlm_lml is:
ml=0m_l=0ml=0
Thus, there is only one allowed value of mlm_lml for an electron in the 2s subshell
