Which subatomic particle has no charge?

The neutron is the subatomic particle that has no charge, meaning it is neutral. Within the nucleus of an atom, neutrons coexist with positively charged protons. The presence of neutrons is crucial because they contribute to the overall mass of the atom without affecting its electrical charge. This neutrality plays a significant role in nuclear stability and the balance of forces within the atom.

The other options—protons and electrons—carry positive and negative charges, respectively, while the term "ion" refers to an atom that has gained or lost electrons, resulting in a net charge. Thus, the key characteristic of the neutron as a particle that does not possess any charge distinguishes it in discussions about atomic structure and behavior.