{ syn. }

{ syn. }

72.168 %

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27.835 %

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{ syn. }


305 351 338 - 405-501

Rubidium (Latin rubidus: deep red, because of two characteristic red spectral lines ) is a chemical element with the chemical symbol Rb and atomic number 37 in the periodic table it is in the 1st main group and is one of the alkali metals. The soft, silvery- white lustrous metal ignites spontaneously on contact with air.


Rubidium was discovered spectroscopically in 1861 by Robert Wilhelm Bunsen and Gustav Kirchhoff as an impurity in lepidolite, as they analyzed the mineral water of the newly developed Maxquelle in Bad Durkheim. Bunsen was able to make rubidium from the source water and to isolate it from other alkali metal salts. Bunsen had to process 44200 liters Dürkheimer spring water to isolate 9 g RbCl.


Rubidium belongs to the group of incompatible elements and usually occurs together with them in increased concentrations. The item comes in small concentrations present in some minerals such as leucite, pollucite and Zinnwaldite. Lepidolite contains up to 1.5% rubidium. Only in recent years, independent rubidium minerals were discovered, such as Rubiklin ( a rubidium aluminum silicate), and Voloshinit and rubidium Ramanit ( Rubidiumpentaborat tetrahydrate).


Like the other alkali metals rubidium is unstable in air and oxidized. With water it reacts very violently to form rubidium hydroxide and hydrogen, which ignites in the air normally. With mercury, it forms an amalgam with the metals gold, cesium, sodium, and potassium, it is alloyed. Rubidium compounds color flames dark red (hence the name of the element ). Rubidium is a strong reducing agent. Metallic rubidium, can be prepared by reduction of rubidium chloride calcium in vacuo.


Of the two naturally occurring isotopes, only 85 Rb is stable, 87Rb is a beta emitter and decays to 87Sr. With an extremely long half-life of about 48 billion years its radioactivity is very low. The ratio of Rb and Sr isotope in rocks is used for radiometric dating.


Rubidium and its compounds have only a small range of applications and are mainly used in research and development. Use possibilities as:

  • Getter in vacuum tubes,
  • Cathode coating,
  • Tracer in PET perfusion of the myocardium,
  • Rubidiumuhren as timing standards ( atomic clock )
  • Since here cheap laser diodes are demonstration of laser cooling for the relevant wavelengths are available ( thus relatively easy production of a Bose -Einstein condensate ).


For the detection of rubidium can use his red-violet flame coloration. The Spectroscope, a clear emission line at 780.0 nm shows Quantitatively, this can be use in flame photometry for the determination of Rubidiumspuren. In polarography rubidium shows a reversible cathodic step at -2.118 V ( vs. SCE ). It must be used as the base electrolyte quaternary ammonium compounds ( for example, 0.1 M tetramethylammonium here ) because other alkali or alkaline earth metal ions have very similar half-wave potentials.


Plant rubidium is probably not essential, in animals, it seems to be essential for the normal course of gestation. Rubidiumbedarf the human is likely to be less than 100 micrograms per day. With the usual mixed diet he comes out to about 1.7 mg per day. A Rubidiummangel is to be expected with this offer just as a nutritive Rubidiumbelastung. Tea and coffee - Arabica coffee has the highest rubidium content, which was found in food ( Arabica bean: 25.5 to 182 mg / kg dry matter) - provide adults on average 40 % of the food consumed Rubidiummenge. Rubidium acts in the central nervous system, and influences the concentration of the neurotransmitters, a use of rubidium as antidepressant agent is discussed. A Rubidiummangel may be present in dialysis patients.


Rubidium is pyrophoric and reacts very violently with water. Rubidium from safety is in dry mineral oil, to be kept in vacuum or in an inert gas atmosphere.


Oxides and hydroxides

  • Rubidium Rb2O
  • Rubidiumperoxid Rb2O2
  • Rubidiumhyperoxid RbO2
  • Rubidiumozonid RbO3
  • Rubidium RbOH


  • Rubidium RbCl
  • Rubidium RbBr
  • Rubidiumiodid RbI
  • Rubidiumtriiodid RbI3

Other links

  • Rubidium RbNO3
  • Rubidium Rb2SO4
  • Rubidiumhydrogensulfat RbHSO4
  • Rubidiumchlorat RbClO3
  • Rubidiumperchlorat RbClO4
  • Rubidiumbromat RbBrO3
  • Rubidiumiodat RbIO3
  • Rubidiumperiodat RbIO4
  • Rubidiumchromat Rb2CrO4
  • Rubidiumdichromat Rb2Cr2O7
  • Rubidiumhydrogencarbonat RbHCO3
  • Rubidiumdithionat Rb2S2O6
  • Rubidium CH3COORb
  • Rubidiumformiat HCOORb
  • Rubidiumhydrid RbH
  • Rubidium amides RbNH2
  • Rubidiumazid RBN3
  • Rubidiumselenid Rb2Se