I've come to the point in my homework discussing the above, and more specifically, energy levels, wave functions, excited states etc.. And while I can locate an appropriate formula and plug-n-chug, I'm finding that I have no clue what these equations and numbers actually mean. And(in my personal opinion..) this book is terrible. It seems as though, rather than giving clear concise derivations, detailed examples with redefinition of variables, the author is more interested in historical context and the physicist's personal details. Which, don't get me wrong, is really interesting, but the fact that the discovery of the Photoelectric effect annoyed Hertz isn't going to help me understand why incident light on metal emits electrons. I digress.. My point is, does anyone know of any good resources that would be more helpful than this book(or my brilliant professor whose accent is so thick I get almost nothing from lecture). I figure having a good source to refer back to will be more efficient than asking a million questions here.