Caesium or cesium[note 1] is a chemical element wi seembol Cs an atomic nummer 55. It is a saft, sillery-gowd alkali metal wi a meltin pynt o 28 °C (82 °F), which maks it ane o anly five elemental metals that are liquid at or near ruim temperatur.[note 2] Caesium is an alkali metal an haes pheesical an chemical properties seemilar tae those o rubidium an potassium. The metal is extremely reactive an pyrophoric, reactin wi watter even at −116 °C (−177 °F). It is the least electronegative element havin a stable isotope, caesium-133. Caesium is mined maistly frae pollucite, while the radioisotopes, especially caesium-137, a fission product, are extractit frae waste produced bi nuclear reactors.
Twa German chemists, Robert Bunsen an Gustav Kirchhoff, discovered caesium in 1860 bi the newly developed method o flame spectroscopy. The first smaa-scale applications for caesium wur as a "getter" in vacuum tubes an in photoelectric cells. In 1967, a specific frequency frae the emission spectrum o caesium-133 wis chosen tae be uised in the definition o the seicont bi the Internaitional Seestem o Units. Syne then, caesium haes been widely uised in atomic clocks.
Syne the 1990s, the lairgest application o the element haes been as caesium formate for drilling fluids. It haes a range o applications in the production o electricity, in electronics, an in chemistry. The radioactive isotope caesium-137 haes a hauf-life o aboot 30 year an is uised in medical applications, industrial gauges, an hydrology. Altho the element is anly mildly toxic, it is a hazardous material as a metal an its radioisotopes present a heich heal risk if released intae the environment.
Notes
↑Caesium is the spellin recommendit bi the Internaitional Union o Pure an Applee'd Chemistry (IUPAC).[5] The American Chemical Society (ACS) haes uised the spellin cesium syne 1921,[6][7] follaein Webster's New International Dictionary. The element wis named efter the Latin word cæsius, meanin "bluish gray".[8] Hence, an alternative orthography is cæsium. Mair spellin explanation at ae/oe vs e.
↑Alang wi rubidium (39 °C [102 °F]), francium (estimatit at 27 °C [81 °F]), mercur (−39 °C [−38 °F]), an gallium (30 °C [86 °F]); bromine is an aa liquid at ruim temperatur (meltin at −7.2 °C, 19 °F) but it is a halogen, nae a metal.
↑Internaitional Union o Pure an Applee'd Chemistry (2005). Nomenclature o 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. ISBN0-8412-3999-1.
↑OED entry for "caesium". Second edition, 1989; online version June 2012; accessed 07 September 2012. Earlier version first published in New English Dictionary, 1888.
Freemit airtins
Caesium or Cesium at The Periodic Table o Videos (Varsity o Nottingham)