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?
From the point of just moving the charge, yes, it’s called antimatter. Antielectrons are positive, antiprotons are negative. From the mass point of view though it would be a different kind of physics altogether since electrons have virtually no mass compared to the other two particles, and protons don’t exist as a particle-wave duality, so neither protons or electrons would act the same by just switching them out in a Bohr atom model arrangement. Maybe someone with more in depth knowledge can give additional or better reasons.
They do, but protons have a much shorter wavelength due to their greater mass.