The "Spin Quantum Number" describes the spin (intrinsic angular momentum) of the electron within that orbital, and gives the projection of the spin angular momentum S along the specified axis
Applicable units are those of quantitykind:SpinQuantumNumber
http://en.wikipedia.org/wiki/Quantum_number
https://cdd.iec.ch/cdd/iec61987/iec61987.nsf/ListsOfUnitsAllVersions/0112-2---62720%23UAD371
The "Spin Quantum Number" describes the spin (intrinsic angular momentum) of the electron within that orbital, and gives the projection of the spin angular momentum S along the specified axis
$s^2 = \hbar^2 s(s + 1)$, where $s$ is the spin quantum number and $\hbar$ is the Planck constant.
http://www.iso.org/iso/catalogue_detail?csnumber=31894