ELI5: Explain Like I'm 5

Nuclear model

The nuclear model is like a tiny solar system inside an atom. Just like the Earth orbits the Sun, in a nuclear model the protons and the neutrons orbit each other. This system is held together by an invisible force called the strong nuclear force. This strong force is strong enough to keep the protons and neutrons together, even though they have the same electric charge and should push each other away.