Why do electron-electron-interactions raise the energy level?

[Cassidyzialle]

Hi,

This is probably a really simple question, I am just trying to get my head around why electron-electron-interactions raise the energy level. If electrons repulse each other, why does this cause the energy levels to increase?

Thanks

 

[fleem]

I'll assume you know that energy is conserved, and that by "raise the energy level" you mean energy is transferred from one electron to the other, which raises that other's energy level. For example, an electron is fired into an atom and it might raise the energy of one of the orbiting electrons.

When an incident electron strikes an orbiting electron, depending on the angle, phase, and position it strikes, it might speed up the orbiting electron, slow it down, or do neither. However, if the orbiting electron is already at its ground state, then it can't be slowed down any further. So one can make the statement, "If an electron is fired at an orbiting electron that is at its ground state, then the energy level of the orbiting electron will either stay the same or be raised"