Okay, bear with my ignorance. 1. Excited state and ground sate Isn't ground state the highest stationary state occupied by valence electrons, while excited state the next highest stationary state(s) where the valence electron(s) can jump to? If yes, then why do all books talk about the ground states being the lowest stationary states and then everything else after that are excited sates? For example, how on earth can N=2(N =Quantum principle number) for Uranium be an excited state? 2. We can best describe electrons as wavelike, more than "point(dot)-like" in most cases. No queston asked. However, how can we visualize that wave -like- thing as having a negative sign?