A subatomic particle with a mass of a proton and no electric charge. It is found in the nuclei of all atoms except hydrogen-1. A free neutron is unstable and decays to form a proton and an electron with a half life of 22 minutes. Because they have no electric charge, neutrons easily penetrate matter, including human tissue. They constitute, therefore, a serious health hazard. When a neutron strikes certain nuclei, such as that of uranium-235, it fissions those nuclei, producing additional neutrons in the process. The chain reaction thus initiated is the basis for nuclear weapons and nuclear power.

See Also

Nuclear Fission; Radioactivity