What is the relative mass of a neutron?

The relative mass of a neutron is approximately 1. This is based on the atomic mass unit scale, where protons and neutrons have a relative mass of about 1, while electrons have a much smaller mass and are often considered negligible in this context. The total mass of an atom is primarily determined by the number of protons and neutrons in its nucleus, since they are significantly heavier than electrons. Therefore, in the context of atomic structure, stating that the relative mass of a neutron is 1 helps establish its scale in comparison to protons and the nearly negligible addition of electrons to the total mass of an atom.