Which particle in an atom has no charge?

The particle in an atom that has no charge is the neutron. Neutrons reside in the nucleus alongside protons and contribute to the mass of the atom, but unlike protons, which have a positive charge, and electrons, which have a negative charge, neutrons are electrically neutral. This neutrality allows neutrons to stabilize the nucleus and influence the atomic mass without affecting the overall charge of the atom.

Understanding the roles of these particles is fundamental in atomic theory. Protons determine the identity of the element and its positive charge, while electrons are involved in chemical bonding and reactions due to their negative charge. Ions, on the other hand, are atoms or molecules that have lost or gained electrons, resulting in a net charge. Thus, neutrons' absence of charge is what differentiates them from these other particles.