Radioactive Decay

Abstract

Approximately 1800 nuclides have been discovered thus far, and the majority of them are unstable. Unstable nuclei decay by spontaneous fission, a-particle, β-particle, or γ-ray emission, or electron capture, in order to achieve stability. The stability of a nuclide is governed by the structural arrangement and binding energy of the nucléons in the nucleus. One criterion of stability is the neutron-to-proton ratio (N/Z) of the stable nuclides; the radionuclides decay to achieve the N/Z of the nearest possible stable nuclide. Radioactive decay by particle emission or electron capture changes the atomic number of the radionuclide, whereas decay by x-ray emission does not.