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n. Symbol Cs
A soft, silvery-white ductile, metallic element that is the most electropositive and alkaline of the elements and is used in atomic clocks and photoelectric cells and to catalyze hydrogenation of some organic compounds. The fundamental unit of time in the International System, the second, is based on the frequency of radiation between two energy states in an atom of the Cs-133 isotope. Atomic number 55; atomic weight 132.905; melting point 28.44°C; boiling point 671°C; specific gravity 1.873; valence 1. See Periodic Table.
[From Latin caesius, bluish gray (from its blue spectral lines).]
(Elements & Compounds) the usual US spelling of caesium
ce•si•um(ˈsi zi əm)
a rare highly reactive soft metallic element of the alkali metal group used chiefly in photoelectric cells. Symbol: Cs; at. wt.: 132.905; at. no.: 55; sp. gr.: 1.9 at 20°C; melts at 28.5°C.
[1861; < Latin caesium, neuter of caesius bluish gray (see -ium2); so named from the blue lines in its spectrum]
Symbol Cs A soft, easily shaped, silvery-white element that is an alkali metal. It is liquid at room temperature and is the most reactive of all metals. Cesium is used to make photoelectric cells, electron tubes, and atomic clocks. Atomic number 55. See Periodic Table.
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|Noun||1.||cesium - a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal|
metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.
cesium 137 - a radioactive isotope of cesium used in radiation therapy
pollucite - a rare mineral that is an important source of cesium