Atoms of a single element which have differing masses. Isotopes are either stable or unstable (radioactive). [[radioisotope|Radioisotopes]] emit particulate (alpha, beta) or electromagnetic (gamma) [[radiation]] as they transform or [[decay]] into stable isotopes. Daughter products produced by primary distintegration or [[irradiation]] are isotopes. See also [[ZA|Z/A]], [[alpha particle]], [[beta particle]], and [[gamma ray]].