Rubidium is a chemical element in the Periodic Table with an atomic number of 37 and a chemical symbol of Rb. This chemical element belongs to the group 1 elements in the Periodic Table, known also as Alkali Metals. Rubidium shares numerous group trades with other Alkali Metal elements in terms of chemical and physical properties, and it appears as a silvery-white metal.


Rubidium is highly reactive when it comes to water, air, and other chemical elements. It forms various oxides, peroxides and compounds. Its strong, basic oxides and its low electronegativity are similar to the ones of other Alkali Metals elements. Rubidium is a non-radioactive chemical element and while it does not serve any nutritional functions for living organisms, it has various applications and uses in many industries, including metallurgy, firework manufacturing, electromagnetism, and so on. Because of its vigorous reaction to water, Oxygen and other chemical elements Rubidium needs to be handled with great care and it is usually stored in compartments filled with mineral oil.


Physical Characteristics of Rubidium

This chemical element is soft, brittle, and docile like the rest of the Alkali Metal elements in the Periodic Table. In terms of physical characteristics Rubidium shares similarities to other Alkali Metals as it is silvery-white in color and appears in a solid natural state. Rubidium can easily become a liquid because of its extremely low melting point. When it’s subjected to a flame test this chemical element turns the flame color into vibrant yellowish-violet hues. It has a relatively low density compared to other chemical elements, but it is much denser than some of the other Alkali Metal elements in the Periodic Table.


Chemical Properties of Rubidium


Atomic Number – 37

Group – 1

Period – 5

Block – s

Electronic Configuration – 5s1

Relative Atomic Mass – 85.467 (85.4678 g/mol)

Molecular Weight – 85.467

Electronegativity – 0.82

Density (G CM-3) – 1.532 g/cm3 at room temperature, 1.46 g/cm3 in a liquid state

Melting Point – 312.45 K; 39.30 °C; 102.74 °F

Boiling Point – 961 K; 688 °C;1270 °F

Atomic Radius – 248pm

Isotopes – 32

Electronic Shell – 2, 8, 18, 8, 1


Discovery of Rubidium

In 1861 two German scientists, named Robert Bunsen and Gustav Kirchhoff, discovered the presence of a new chemical element in a lepidolite mineral through the practice of spectroscopy. After they managed to fully isolate the new component from the ore they inspected the element through spectroscopy and decided to name it Rubidus (meaning “deep red” in Latin) because of its distinctive deep red color specter.


Recognized by: Robert Bunsen and Gustav Kirchhoff (1861)

Known and discovered by: Robert Bunsen and Gustav Kirchhoff (1861)

Named by: Robert Bunsen and Gustav Kirchkoff


Uses and role of Rubidium

While Rubidium does not play any key roles for the biological purpose of living organisms, this Alkali Metal element has various uses and applications in the chemical and electronic industries.


Because of its distinctive chemical properties Rubidium is largely used in electronics for the manufacturing of various lasers and diodes, and even in the manufacturing of thermoelectric generators. Several compounds of Rubidium are used in firework manufacturing and other pyrotechnics for purple-colored effects. Another application of Rubidium is found in atomic clocks. Rubidium’s radioisotopes are used in nuclear medicine for the location of brain tumors. It can be used in glass manufacturing, in the telecommunication industry, and even in metallurgy, because it forms various alloys with Cesium, Potassium, Sodium, Iron, Gold, and amalgams with Mercury.


Rubidium on Earth

Rubidium is considered as part of the incompatible elements because of its large ionic radius, just like Cesium, Zirconium, Barium, Strontium, and other similar elements with large ionic radii or with large ionic valances. However, it does occur naturally on Earth in various minerals, including pollucite, leucite, zinnwaldite, and carnallite. Rubidium is also found in sea water, but this particular element is most abundant in pegmatite ores. Two of the biggest Rubidium sources on Earth are in Bernic Lake, Canada, and in the island of Elba in Italy.


Rubidium is found in living organisms as part of their intracellular fluids. Rubidium ions are not toxic for the human body if they are administered in small dosages. Rubidium has a biological half-life of between 31 and 46 days in the human body.



A while ago it was discovered that patients suffering from manic depression illnesses could be treated with Rubidium. Medical experts used this chemical element as part of administered drugs in patients suffering from depression as a way to supplement their organism with Rubidium Chloride. It was discovered that such patients suffered from depletion in Rubidium and that Rubidium supplements helped them battle their manic depression illnesses.