Rubidium is a chemically reactive, silvery-white metallic element of the alkali metals’ group. It is one of the most electropositive and alkaline elements. Rubidium was discovered spectroscopically in 1860 in the mineral lepidolite, which is now the element’s main commercial ore. They named the element after the ruby red lines prominent in its spectrum. Metallic rubidium is silvery white and very soft. After cesium, it is the most active of the alkali metals. It tarnishes immediately upon exposure to air and ignites spontaneously to form rubidium oxide. It reacts violently with water.

Rubidium can become liquid at ambient temperature, but only on a hot day given that its melting point is about 40°C. Its flame is yellowish-violet. Rubidium and its salts have few commercial uses. The metal is used in the manufacture of photocells and in the removal of residual gases from vacuum tubes. Rubidium salts are used in glasses and ceramics and in fireworks to give them a purple colour. Potential uses are in ion engines for space vehicles, as working fluid in vapor turbines, and as getter in vacuum tubes. Read the rest of this entry »