1. The problem statement, all variables and given/known data For C atom (2 electrons in 2p orbital) I get L=0,1 or 2 and S=0 or 1: so spin multiplicity/terms (in braket generacy of states) are 1S(1), 3S(3), 1P(3), 3P(9), 1D(5), 3D(15)...for a total of 36 states. I am sure I am overestimating because in reality those should be microstates: microstates are not states while states are mixtures of microstates so no. of indipendent states are no. of indipendents microstates. 2. Relevant equations spin multiplicity: 2S+1 so S=0 => multip 1 (singlet); S=1 => 3 (triplet). When L=0 term is S; L=1 term is P; L=0 term is D. 3. The attempt at a solution Pauli principle + Hund's rule are the only things that come into my mind but I am not really sure if they can help or there is something else I am missing out.