In an atom's nucleus, protons and neutrons are held together by the strong nuclear force, also known as the strong interaction. The strong force is one of the fundamental forces in nature, along with gravity, electromagnetism, and the weak nuclear force. It is responsible for binding the nucleus together despite the electric repulsion between positively charged protons.
The strong force is different from the electromagnetic force, which governs the interaction between charged particles. Unlike the electromagnetic force, the strong force does not depend on the electric charge of particles. Instead, it acts between all quarks (the elementary particles that make up protons and neutrons) and is mediated by particles called gluons.
Neutrons do not have a charge, so they are not directly involved in the electromagnetic interaction between protons. However, the mass of neutrons does play a crucial role in keeping protons together. Neutrons are slightly more massive than protons, and this mass difference contributes to the stability of atomic nuclei.
The extra mass provided by the neutrons helps to overcome the electromagnetic repulsion between protons. The neutrons act as "glue" that binds protons together through the strong force, effectively counteracting the repulsive electric force. This is why stable atomic nuclei typically have a balance of protons and neutrons.
In summary, while neutrons do not have a charge and do not directly participate in electromagnetic interactions, their mass and the strong nuclear force play crucial roles in keeping protons together in an atom's nucleus.