Hi, I have a question about quantum numbers?

Question

I don't really get how quantum numbers work...
I know that N is the energy level,
L is either 0,1,2,3 depending on the spdf
but how do I get ml and ms?
Thanks so much!

Answer 1

ms is easy, its the spin quantum number. Since only two electrons can occupy an orbital, and Pauli Exclusion says they must have two different quantum number sets, then their spin direction makes them different. ms can only be +1/2 or -1/2

ml is called angular momentum quantum number. ml goes from +L to -L in value. It assigns a value to each orbital. For example in a 1s, s has an L of 0, so the only possible ml value is 0, indicating only 1 orbital. 2p would have an L of 1, and could have ml be -1,0,or +1. 3d would have an L of 2, so ml could be -2,-1,0,+1,+2 because d has 5 orbitals.

Remember that L must always be less than or equal to n-1. Level n=1 can only have L=0 (an s). Level n=2 can have s (L=0) or p(L=1) etc...