radioactivity

== English == === Alternative forms === radio-activity === Etymology === From radioactive +‎ -ity or radio- +‎ activity. === Pronunciation === IPA(key): /ˌreɪdɪəʊakˈtɪvɪti/ === Noun === radioactivity (usually uncountable, plural radioactivities) Spontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus. The radiation so emitted; including gamma rays, alpha particles, neutrons, electrons, positrons, etc. ==== Hyponyms ==== (types of radioactive decay): alpha decay beta decay electron capture gamma decay spontaneous fission ==== Derived terms ==== ==== Related terms ==== Units of radioactivity: becquerel curie ==== Translations ==== === See also === half-life === Further reading === Radioactive decay on Wikipedia.Wikipedia