Rubidium is a chemical element with the symbol Rb and atomic number 37. Rb is a soft, silvery-white metallic element of the alkali metal group.

Elemental rubidium is very soft and highly reactive, it has a very rapid oxidation in air. Its compounds have chemical and electronic applications. Rubidium metal is easily vaporized and has a convenient spectral absorption range, making it a frequent target for laser manipulation of atoms.

Rubidium is not known to be necessary for any living organisms. However, like cesium, rubidium ions are handled by living organisms in a manner similar to potassium ions: it is actively taken up by plants and by living animal cells.

Rubidium has one stable isotope,85Rb. The isotope 87Rb which composes almost 28% of naturally occurring rubidium is slightly radioactive, with a half-life of 49 billion years—more than three times longer than the estimated age of the universe.


Rubidium is the second most electropositive of the non-radioactive alkali elements and melts at a temperature of 39.3 °C (102.7 °F). This metal reacts violently with water. In common with potassium (which is slightly less reaction) and cesium (which is slightly more reaction) this reaction is usually vigorous enough to ignite the liberated hydrogen gas. Rubidium has also been reported to ignite spontaneously in air. Like other alkali metals, it forms amalgams with mercury and it can form alloys with gold, cesium, sodium, and potassium. The element and its ions gives a reddish-violet color to a flame. It was named after two strong emission lines in the dark red area of the spectrum.

As a symmetrical effect of rubidium metal's high reactivity toward oxidation and tendency to subsequent formation of the rubidium cation Rb+, this cation, once formed, is very stable, and is normally unreactive toward further oxidative or reductive chemical reactions.


The base value of each unit of ranges between 5 and 12Ð per unit, with up to 2 units being found at any one time.

Presence on Mars: Very Rare

Martian Minerals
Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 6
Group 2 |Argon | Bromine | Cadmium | Gallium | Germanium | Gold | Helium III | Krypton | Molybdenum | Neon | Niobium | Nitrogen | |Palladium | Rhodium | Rubidium | Ruthenium | Scandium | Selenium | Silver | Strontium | Technetium | Titanium | Vanadium | |Yttrium | Zirconium|
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