Hi, I have a helium atom in the excited state of (1s,20p), and I am told that it has 4 corresponding atomic terms. I am supposed to "write down the quantum numbers of these 4 atomic terms". As I understand it, an atomic term is specified by the 2S+1LJ notation, where S is the spin quantum number for the whole atom, L is the orbital angular momentum quantum number for the whole atom, and J is the total angular momentum quantum number for the whole atom. So, looking at the individual electrons, the 1s electron has spin quantum number s=1/2, and orbital angular momentum quantum number l=0. the 20p electron has s=1/2, l=1. I think I am right in saying that only the 20p electron contributes any orbital angular momentum to the atom, so that for the whole atom, L = l = 1, therefore the atomic term should become 2S+1PJ. However, this is where I start to get confused. My notes aren't that clear and there are a lot of L's, S's J's, l's, s's, j's etc. getting thrown around. How am I supposed to determine what S and J are? I am assuming there are only 4 possible combinations of S and J. I thought of doing S = s1+s2 = s+s = 1/2 + 1/2 = 1, therefore Ms = -1,0,1 (not sure if this is relevant) but I was not sure about this and got the impression from my notes this was incorrect. The same goes for saying J=L+S. This would only give me the one atomic term, 3P2, where I need 4 terms. I'd appreciate it if someone could help me out here. Thanks.