Every time I try to understand how forces which hold atoms and molecules together work, I find myself wanting to ask this question: why not the other way around? Could there be an atom which has electrons and neutrons inside, and protons outside?
It feels like a silly question, but is there something we know about the universe we live in that implies that this is not possible?
ELI5 answer: protons and electrons have equal but opposite electromagnetic charges, but they have other qualities that make them dissimilar- for example, protons have a lot more mass than electrons do. It’s those other factors that prevent electrons from clumping in the nucleus.