From what i've read, electrons in a lower energy level have more kinetic enery and momentum to stop "falling" into the positive nucleus. However, when an electron falls from a higher energy level to a lower one, the loss of energy is emitted as a photon. So how does it gain kinetic energy?
Thanks in advance
[Physics] How do electrons in a lower energy level have more kinetic energy
atomselectronsquantum mechanics
Best Answer
I think the confusion comes from mixing up two terms: kinetic energy and energy.
Energy is a sum of kinetic energy and potential energy. Energy states, as is well-known, depend on the quantum number $n$ in ascending order: electrons farther away from the nucleus have greater energy. It is why when photons are emitted the electron transits to a closer-to-the-nucleus orbit.
But kinetic energy indeed is higher for the small-$n$ orbits. This is because they have huge negative potential energy, as they are close to the attracting nucleus, which is "compensated" by huge positive kinetic energy.
Btw, I think that the comment by @CountTo10 is incorrect as (s)he also confuses these terms (no offense!). Please correct me if I got something wrong.