What term describes uncharged elementary particles that have a mass nearly equal to that of a proton?

Neutrons are uncharged elementary particles that are found in the nucleus of an atom, and they have a mass that is very close to that of protons. This characteristic makes them essential in maintaining the stability of atomic nuclei, as they provide the strong force necessary to hold protons together, which are positively charged and repel each other due to electromagnetic forces. The presence of neutrons contributes to the overall atomic mass, but they do not carry any electrical charge, distinguishing them from protons and electrons.

In contrast, quarks are elementary particles that combine to form protons and neutrons, but they are never found in isolation due to a phenomenon called confinement. Electrons are negatively charged particles that orbit the nucleus, and positrons are the antimatter counterparts of electrons with a positive charge. These particles do not have the mass comparable to protons, which solidifies the selection of neutrons as the answer to the question regarding uncharged particles with a mass nearly equal to that of a proton.