Question: A hydrogen atom has one electron. If we heat hydrogen gas up enough, we will completely separate each electron from each hydrogen atom (called "ionization"). What will the spectrum of ionized hydrogen look like ("ionized" means that the electron has already been taken away)? Here's what I wrote: Because its electron is missing, and photons (and light) are created and destroyed by electrons changing energy levels, I would conclude that completely ionized hydrogen would be unable to emit or absorb light, and therefore have no spectrum. This seems reasonable to me, but is it correct?