I know this is a rather basic question, but I'm unable to find it in the book. Frequently the idea of resonance is thrown around, but I don't reallyunderstand WHY it occurs, just that it does. Energy is energy, and I would think that at any level we would see some frequency increase. This is physics and all, but if you can explain, it would help. This is just basic atomic physics.
Energy is absorbed at the molecular level only when the correct quanta of energy is available.
Too much or too little energy is not absorbed.