INORGANIC CHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site 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. 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 is used in radiotherapy. 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 Transport Concepts & Designs (partner site) BACK TO TOP