cesium (Cs)

Cesium.
Justin Urgitis, Wikipedia

A soft, silvery, ductile, metallic element produced as a by-product of zinc refining and by reduction of cesium chloride. It is found mainly as the mineral pollucite. Cesium is one of the alkali metals, found in Group I of the periodic table. It is the most electropositive and alkaline of elements, turns to a liquid at only 28.5°C, and burns spontaneously in moist air. It is used in photoelectric cells, as a catalyst promoter, and to make special glass. The radioisotope cesium-137 can be employed in radiotherapy, but is now rarely used. The cesium (atomic) clock provides the standard measure of time: the electron resonance frequency of the cesium atom is exactly 9,192,631,770 cycles per second. Cesium has also been used in ion propulsion.

Cesium was discovered by Robert Bunsen and Gustav Kirchhoff in Heidelberg, Germany, in 1860. Its name comes from the Latin caesius meaning "sky blue."

atomic number	55
relative atomic mass	132.905
electronic configuration	1s²2s²2p⁶3s²3p⁶4s²3d¹⁰ 4p⁶5s²4d¹⁰5p⁶6s¹
first ionization energy	376 kJ/mol
atomic radius	265 pm
ionic radius	167 pm
relative density	1.87
melting point	28.5°C (83.3°F)
boiling point	690°C (1,274°F)

Related category

• INORGANIC CHEMISTRY

Also on this site:

Encyclopedia of Alternative Energy & Sustainable Living
Encyclopedia of History

BACK TO TOP