Spin quantum number and magnetic field

Question

The total spin is given by S = 1/2 x # unpaired electrons

Example:
Fe3+ —> d^5 —> 5 unpaired electrons
S = 5 x 1/2 = 5/2
ms = + or - 5/2,    + or - 3/2,    + or - 1/2
 

• I was going through my lecture notes and this was on it and i thought ms could only be + or - 1/2 and am confused from where the 3/2 is coming from

Answer 1

Electron Spin Quantum Number

Unlike n, l, and ml, the electron spin quantum number ms does not depend on another quantum number. It designates the direction of the electron spin and may have a spin of +1/2, represented by↑, or –1/2, represented by ↓. This means that when ms is positive the electron has an upward spin, which can be referred to as "spin up." When it is negative, the electron has a downward spin, so it is "spin down." The significance of the electron spin quantum number is its determination of an atom's ability to generate a magnetic field or not. 

ms= +1/2 or -1/2

So, you are correct, ms could only be + or - 1/2.