Hello all, I wonder if anyone can help me with a problem I don't understand about atomic levels. Given an excited state of He with electronic config (1s,2p), I need to find all possible atomic levels. The answer sheet lists 4 levels: 1) S=0, L=1, J=1 2) S=1, L=1, J=1+1=2 3) S=1, L=1, J=1-1=0 These first three I understand, but the fourth: 4) S=1, L=1, J=1 (?) How come J can be equal to 1? Anyone care to explain or point me in the right direction, please?