1. The problem statement, all variables and given/known data how many possible quantum states for a nitrogen atom with electronic configuration of 1s22s22p3 2. Relevant equations ??? 3. The attempt at a solution So, the answer for this question is 20, but I can't for the life of me find out how. The book we're given is Physical Chemistry by Atkins. Quantum state isn't even listed in the index. My professor uses a statistical thermodynamics book by engel & reid, I believe is where he takes these questions from. I don't believe that he is using the phrase quantum states to mean quantum numbers. Please help!