Charge-neutral hadron with a mass of 1.6748 x 10-27 kg, equivalent to 939.573 MeV, and an intrinsic angular momentum, or spin, of ½ (in units of h/2π). The neutron is a nucleon, one of the two basic constituents of all atomic nuclei (apart from 1H, which consists of a single proton). The total number of protons and neutrons in an atomic nucleusCore of an atom, where nearly the entire mass and all positive charge is concentrated. It consists of protons and neutrons. defines its mass numberSum of the number of neutrons and protons in a nucleus. Not to be confused with "atomic mass"., A. Neutrons are stable within the nucleus, but unstable in isolation (t½ = 886±2 s), decay being mediated by a W boson:
Some or all content above used with permission from J. H. Wittke.