So if We Consider Our Proton And our electron a system, that means I have to do work on my system to move this electron a distance r away from this electron, right? So that means work must be done on our system. And because work is a transfer of energy, energy must be transferred into our system. So our overall energy of our system increases as the electron moves away from our nucleus. And that's exactly why placing electrons further away from our nucleus will increase the energy of our system. That's exactly why nature tends to place electrons as close to our atom, as close to our nucleus as possible.