Last revised by Dr Pir Abdul Ahad Aziz Qureshi on 29 Sep 2021

Radioactivity, also known as radioactive decay, describes the process of spontaneous breakdown of unstable (or radioactive) nuclides, with the formation of daughter nuclei and release of subatomic particles and/or gamma radiation. A single decay (a.k.a. disintegration) refers to the degradation of one nuclide into another. 

Modes of decay

Radioactive decay is a stochastic process, i.e. it is probabilistic, and it is impossible to foresee which specific nuclei will decay. Nevertheless, it can be predicted with a high degree of confidence the proportion of any sample of radioactive atoms that will decay in a specified period of time.

History and etymology

Henri Becquerel (1852-1908) discovered radioactivity in 1896 when studying potassium uranyl sulfate 2. Further early advances were made by wife and husband, Marie Skłodowska Curie (1867-1934) and Pierre Curie (1859–1906), who were co-awarded the Nobel Prize in Physics with Becquerel in 1903. It was Marie Curie who coined the term radioactivity 4

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