Chemical Elements History and Information Cesium

About the chemical element Cesium, its symbol, atomic number and weight, who discovered it and when.

The Atomic Elements and Their Uses

(Element) (Symbol) (Atomic number) (Atomic weight)

Cesium Cs 55 132.9054

Discovered by Robert Bunsen and Gustav Kirchhoff of Germany in 1860, cesium is the basis of the time standard. Since there are only a few outer electrons very loosely bound to the cesium atom, it is easy to measure their radiation. The radiation of a cesium electron was computed in 1958 to be 9,192,631,770 cycles per second--now used as an absolute standard for a second's time.