Chemical Element: rubidium

(Modern Latin: from Latin rubidus, "red"; from the red lines in its spectrum; metal)

Chemical-Element Information

Symbol: Rb
Atomic number: 37
Year discovered: 1861

Discovered by: Gustav Robert Kirchhoff (1824-1887), a German physicist; and Robert Wilhelm Bunsen (1811-1899), a German chemist.


  • Rubidium was discovered, in 1861, spectroscopically by Robert Bunsen and Gustav Kirchoff as an impurity associated with samples of the mineral lepidolite (a form of mica).
  • In their report, made in 1861, Bunsen and Kirchhoff told how they named the new element: “The magnificent dark red color of these rays of the new alkali metal led us to give this element the name rubidium and the symbol Rb from ‘rubidus’, which, with the ancients, served to designate the deepest red.”
  • Rubidium was discovered, in 1861, spectroscopically by Robert Bunsen and Gustav Kirchoff as an impurity associated with samples of the mineral lepidolite (a form of mica).

    • Atomic clocks?

  • A modern cesium atomic clock can tell time accurately to 15 digits behind the decimal point; however, these machines are running up against the limits of technology and physics.
  • In the search for something even more accurate, as of the year 2000, a research team from the United States and another from France have succeeded independently of each other in creating rubidium-run atomic clocks that have the potential to exceed the cesium standard.
  • The Laboratoire Primaire du Temps et des Fréquences (LPTF) in Paris holds the current world record of an inaccuracy of 1.1X1015, which means in practical terms that its clock would lose one second every 30 million years.
  • Scientists now believe that they can exceed the short-term stability of cesium clocks by a factor of 10.
  • Promising experiments using single ions and laser-cooled rubidium atoms suggest the potential for one day achieving measurements of the second up to 17 or 18 digits behind the decimal point.
  • Apparently, so far, there is no technical application for such a high level of precision; however, that would not stop any number of radio astronomers or cutting-edge researchers from immediately acquiring such an instrument the moment it becomes available.

Name in other languages:

French: rubidium

German: Rubidium

Italian: rubidio

Spanish: rubidio


—The information in the last six paragraphs (above)
is based on an article in the Frankfurter Allegemeine Zeitung;
“Atomic Clocks? Yes, Please! Subatomic Particles
Drive World’s Most Accurate Timekeepers”
by Max Rauner; November 3, 2000; Page 8.

Information about other elements may be seen at this Chemical Elements List.

A special unit about words that include chemo-, chem- may be seen here.