Rubidium is the chemical element with atomic number 37, symbol Rb. It is an alkali metal, soft and silvery, whose melting temperature is only 39.3 ¡ã C. It can be kept liquid at room temperature thanks to the phenomenon of supercooling, such as cesium and gallium.

Its name comes from the Latin rubidus (dark red), due to the red color of the spectral lines which enabled Robert Wilhelm Bunsen and Gustav Kirchhoff to detect it in 1861 in lepidolite. He was isolated the following year by Bunsen.

Like other alkali metals, it ignites spontaneously on contact with air and reacts violently with water.

In the form of Bose-Einstein condensate, it has the property of reducing the speed of light passing through it to less than 60 km / h.
Rubidium has 32 known isotopes, with a mass number varying between 71 and 102, and 12 nuclear isomers. Only two of these isotopes are found in nature, 85Rb (72.2%), the only stable isotope of rubidium (making it a monoisotopic element) and radioactive 87Rb (27.8%). Natural rubidium is thus radioactive enough to impress a photographic film in thirty to sixty days6. Rubidium is assigned a standard atomic mass of 85.4678 (3)
Photovoltaic cells: it is used in alloy with cesium.
Tempered safety glass: the addition of rubidium carbonate (Rb2CO3) or rubidium oxide (Rb2O) allows safety glass to be obtained by tempering.
Review of myocardial perfusion in nuclear medicine: due to its similarity to potassium, the radioactive positron emitter isotope, 82Rb, of short half-life (75 seconds), is used as an indicator of PET ischemia and use as an 81 m krypton generator in pulmonary scintigraphy (Rb81).
Manufacture of certain nooanaleptic drugs.
Atomic physics: The rubidium atom (both its isotopes 85 and 87) is very frequently used for experiments in atomic physics. Indeed, certain transitions of this atom correspond to conventional laser wavelengths (780 nm for the 5s-5p transition in particular), which facilitates the experiments. Among others, rubidium can be used for the construction of atomic clocks using the hyperfine transition from 87Rb to 6.834 682 611 GHz 7.
The use of this transition makes it possible to obtain compact and low-cost commercial clocks, with a relative frequency stability of 5 ¡Á 10−11 (ie a possible error of 1 second over a little over 600 years 8). There are also clocks called ¡°atomic fountains¡±, operating with laser-cooled and manipulated 87Rb, which reach much better relative frequency stabilities, between 10−13 and 10−14 9.

Gas sensor for cathode ray tube and electronic tube: it is used as a getter (gas molecule sensor) to complete the vacuum.
It is sometimes used to get the purple color in fireworks




rhenium    germanium    zirconium     cadmium     hafnium

      barium   lithium     beryllium     strontium     calcium

      Tantalum    gadolinium    samarium      yttrium   ytterbium

       Lutetium    praseodymium   holmium     erbium   thulium     dysprosium

       terbium   europium  lanthanum   cerium   neodymium  scandium 

         rubidium    cesium