Rubidium

Rubidium, chemical element, symbol Rb; for physical constants see Periodic Table. Rubidium was discovered spectroscopically by Robert Bunsen and Gustav Kirchhoff in 1861. It occurs in lepidolite and several other minerals. The element is prepared by reducing the chloride with calcium. Rubidium is a silver-white, soft, low-melting, reactive metal of the alkali metal group. It can be liquid at room temperature and ignites spontaneously in air. Rubidium and its compounds are used in ion propulsion systems, vapor turbines, thermoelectric generators, batteries, photo cells, and special glasses.