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caesium

British  
/ ˈsiːzɪəm /

noun

  1. a ductile silvery-white element of the alkali metal group that is the most electropositive metal. It occurs in pollucite and lepidolite and is used in photocells. The radioisotope caesium-137 , with a half-life of 30.2 years, is used in radiotherapy. Symbol: Cs; atomic no: 55; atomic wt: 132.90543; valency: 1; relative density: 1.873; melting pt: 28.39±0.01°C; boiling pt: 671°C

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Example Sentences

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Caesium irradiators, which have long been used to eliminate pathogens in supplies of blood as well as for research applications, rely on small capsules of radioactive caesium chloride encased in a lead-covered box.

From Nature • May 9, 2016

Caesium clocks have proved that an absolute measure of time is - impossible.

From BBC • Oct. 3, 2014

The most popular videos, such as Caesium and Oxygen, are of reactive elements, and surprisingly, even a synthetic element like hassium has attracted 32,000 views.

From Science Magazine • May 26, 2011

Caesium resembles potassium in its properties, and exists only in exceedingly small quantities.”

From Scientific American • Mar. 25, 2011

Caesium sulphate, Cs2SO4, may be prepared by dissolving the hydroxide or carbonate in sulphuric acid.

From Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" by Various

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