Editing Nucleon (section)

===Stability===
A neutron in free state is an unstable particle, with a [[half-life]] around ten minutes. It undergoes [[beta decay|{{SubatomicParticle|Beta-}} decay]] (a type of [[radioactive decay]]) by turning into a proton while emitting an electron and an [[electron antineutrino]]. This reaction can occur because the mass of the neutron is slightly greater than that of the proton. (See the [[Neutron]] article for more discussion of neutron decay.) A proton by itself is thought to be stable, or at least its lifetime is too long to measure. This is an important discussion in particle physics (see ''[[Proton decay]]'').

Inside a nucleus, on the other hand, combined protons and neutrons (nucleons) can be stable or unstable depending on the [[nuclide]], or nuclear species. Inside some nuclides, a neutron can turn into a proton (producing other particles) as described above; the reverse can happen inside other nuclides, where a proton turns into a neutron (producing other particles) through [[beta decay|{{SubatomicParticle|Beta+}} decay]] or [[electron capture]]. And inside still other nuclides, both protons and neutrons are stable and do not change form.