I understand how it is that electrons move from one energy state to another, however I've not been able to find anywhere that describes why an atom has any particular states.

Why should an atom of one element have a particular set of energy states and an atom of another element have a different set of energy states?

  • $\begingroup$ Because the other element has a different number of protons, so the potential is different, leading to different solutions for the wave functions. $\endgroup$ – Jon Custer May 15 '16 at 18:19
  • $\begingroup$ @JonCuster, So it's the protons that cause the potential to be different and therefore the different energy states? Is it exclusively the different number of protons? $\endgroup$ – TheMightyLlama May 15 '16 at 18:50
  • $\begingroup$ The protons have the charge that determines the potential, so yes. $\endgroup$ – Jon Custer May 15 '16 at 18:53
  • $\begingroup$ @JonCuster But don't forget that the situation gets complicated very fast because the presence of all the other electrons also strongly influence the potential, not to mention the effect of exchange symmetry. $\endgroup$ – garyp May 15 '16 at 22:08
  • $\begingroup$ @garyp - while true, at the heart of it (pun intended) is the different charge on the nucleus that leads inevitably to a different set of states. Now, the electrons do squabble amongst themselves to get the best seats in the house, but the interactions are different for each atom only because of the different potential to deal with. $\endgroup$ – Jon Custer May 15 '16 at 22:42