Caesium-137

"Cesium 137" redirects here. For the band, see Cesium 137 (band).

Caesium-137, 137Cs
A sealed caesium-137 radioactive source
General
Symbol137Cs
Namescaesium-137, 137Cs, Cs-137
Protons (Z)55
Neutrons (N)82
Nuclide data
Natural abundance0 (trace)
Half-life (t1/2)30.05±0.08 years[1]
Isotope mass136.907 Da
Spin7⁄2+
Parent isotopes137Xe (β−)
Decay products137mBa
137Ba
Decay modes
Decay modeDecay 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-137 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.

  1. ^ Cite error: The named reference cea was invoked but never defined (see the help page).
  2. ^ "137
    55    Cs
    82"    . WWW Table of Radioactive Isotopes. LBNL Isotopes Project - LUNDS Universitet. Archived from the original on 22 May 2015. Retrieved 14 March 2009.
  3. ^ 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..
  4. ^ 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.
  5. ^ 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.
  6. ^ OED entry for "caesium". Second edition, 1989; online version June 2012. Retrieved 7 September 2012. Earlier version first published in New English Dictionary, 1888.
  7. ^ 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.