If we have 2 electrons in the 1st energy level named X & Y, and one electron in the 2nd energy level named Z.
If the electron X was excited and transferred to the higher energy level, why didn't Z replace it in the 1st energy level?
Why don't we say that there is a type of nuclear gravity, and it increases when the atom becomes unstable and that gravitates Z electron towards the nucleus instead of the excited one?