Caesium-137
A sealed caesium-137 radioactive source | |
| General | |
|---|---|
| Symbol | 137Cs |
| Names | caesium-137 |
| Protons (Z) | 55 |
| Neutrons (N) | 82 |
| Nuclide data | |
| Natural abundance | 0 (trace) |
| Half-life (t1/2) | 30.04 years[1] |
| Isotope mass | 136.907 Da |
| Spin | 7⁄2+ |
| Parent isotopes | 137Xe (β−) |
| Decay products | 137mBa 137Ba |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| β- (beta decay) | 0.5120[2] |
| γ (gamma-rays) | 0.6617 |
| Isotopes of caesium Complete table of nuclides | |
Caesium-137 (137
55Cs), cesium-137 (US),[7] or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nuclear weapons. Trace quantities also originate from spontaneous fission of uranium-238. It is among the most problematic of the short-to-medium-lifetime fission products. Caesium has a relatively low boiling point of 671 °C (1,240 °F) and easily becomes volatile when released suddenly at high temperature, as in the case of the Chernobyl nuclear accident and with atomic explosions, and can travel very long distances in the air. After being deposited onto the soil as radioactive fallout, it moves and spreads easily in the environment because of the high water solubility of caesium's most common chemical compounds, which are salts. Caesium-137 was discovered by Glenn T. Seaborg and Margaret Melhase.
- ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory.
- ^ International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. pp. 248–49. Electronic version..
- ^ Coghill, Anne M.; Garson, Lorrin R., eds. (2006). The ACS Style Guide: Effective Communication of Scientific Information (3rd ed.). Washington, D.C.: American Chemical Society. p. 127. ISBN 978-0-8412-3999-9.
- ^ Coplen, T. B.; Peiser, H. S. (1998). "History of the recommended atomic-weight values from 1882 to 1997: a comparison of differences from current values to the estimated uncertainties of earlier values" (PDF). Pure Appl. Chem. 70 (1): 237–257. doi:10.1351/pac199870010237. S2CID 96729044.
- ^ OED entry for "caesium". Second edition, 1989; online version June 2012. Retrieved 7 September 2012. Earlier version first published in New English Dictionary, 1888.
- ^ Caesium is the spelling recommended by the International Union of Pure and Applied Chemistry (IUPAC).[3] The American Chemical Society (ACS) has used the spelling cesium since 1921,[4][5] following Webster's New International Dictionary. The element was named after the Latin word caesius, meaning "bluish grey".[6] In medieval and early modern writings caesius was spelled with the ligature æ as cæsius; hence, an alternative but now old-fashioned orthography is cæsium. More spelling explanation at ae/oe vs e.