Question

Do the neutrons in the atom's nucleus keep two or more protons from moving apart?

Answer 1

Massive nuclear particles engage in the strong nuclear force.........

Explanation:

At short ranges (and nuclear ranges are short, `~=10^-15m`), nucleons, protons and neutrons, engage in the strong nuclear force, one of the four known, fundamental interactions. This is approx. `10^2` times stronger than the electromagnetic force (and it needs to be, why?).

Anyway, if you want a more sofisticated answer, you will have to find a particle physicist. Most chemists, including me, do not have too much clue about this force.