The focus for me right now is the quantum mechanics, including quantum states and how they vary in energy as they emit or absorb energy. The "ground state" of an atom always starts as one, and takes more energy to move it from 1 to 2 (or s to p), and the reverse of this. It seems logical to me up to the very last bit...What I am puzzled by is why 1 is the ground state and not 0, as it also appears logical to me that when, say, a hydrogen atom with no charge is dissolved and donates its single electron, that the hydrogen ion atom (just the nucleus) now is at state 0. I suspect that my mistake is that I am trying to assign a certain amount of energy which only applies to electrons, and trying to shove the nucleus into the same conceptual box.