Physical Properties:

 Rubidium is a very soft silvery-white metal that violently combines with water, setting fire to the liberated hydrogen, and may ignite in air. When it burns, its flame is a yellowish-violet color. It is solid at 298K and liquid at 313K. It forms amalgams with mercury and alloys with gold, cesium, potassium and sodium.

 

History:

 Rubidium was discovered by Robert Bunsen  and Gustave Kirchoff in 1861 in Germany. Its name is from the Latin word Rubidious meaning red, the color that its salt burns

Source

Rubidium is the 16th most abundant element in the earth's crust. It occurs in the minerals pollucite, carnallite, leucite and lepidolite, from which it is recovered commercially. Potassium minerals and brines also contain this element and are a further commercial source.

Uses

Rubidium is used little outside research. It is easily ionized so was considered for use in ion engines, but was found to be less effective than cesium. It has been proposed for use as a working fluid for vapor turbines and in thermoelectric generators. It is used as a photocell component and in special glasses. Because rubidium can be easily ionized, it has been considered for use in "ion engines" for space vehicles; however, cesium is somewhat more efficient for this purpose. It is also proposed for use as a working fluid for vapor turbines and for use in a thermoelectric generator using the magnetohydrodynamic principle where rubidium ions are formed by heat at high temperature and passed through a magnetic field. These conduct electricity and act like an amateur of a generator thereby generating an electric current. Rubidium is used as a getter in vacuum tubes and as a photocell component.  RbAg4I5 is important, as it has the highest room conductivity of any known ionic crystal. At 20oC its conductivity is about the same as dilute sulfuric acid. This suggests use in thin film batteries and other applications. The picture below show the use of laser cooled rubidium atoms in an atomic clock, which will increase the clocks accuracy by a factor of 30.

Rubidium has five principle energy levels. Its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹. This configuration leaves it with a single valence electron in its outer shell. This electron is easily lost to form a more stable existence.

In 1861, rubidium was discovered spectroscopically when a very distinctive, ruby-red colour spectral line was observed. The new element was given the name rubidium, from the Latin name rubidus, meaning "deep red".

This is the physical appearance Rubidium. As you can see it is very soft and a silvery color.

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