Symbol Rb
Atomic Number 37
Atomic Mass 85.4678 g.mol -1
Discovered by Gustav Kirchhoff and Robert Bunsen

Chemical Properties of Rubidium

Group 1 Melting point 39.30°C, 102.74°F, 312.45 K
Period 5 Boiling point 688°C, 1270°F, 961 K
Block s Density (g cm−3) 1.53
Atomic number 37 Relative atomic mass 85.468  
State at 20°C Solid Key isotopes 85Rb, 87Rb
Electron configuration [Kr] 5s1 CAS number 7440-17-7
ChemSpider ID 4512975 ChemSpider is a free chemical structure database

What is Rubidium?

  • The element is a member of the alkali metal group 1 of the periodic table.
  • The element has an atomic number of 37 and an atomic mass of 85.
  • The metal is a lithophile metallic element that does not form any minerals of its own.

Uses of Rubidium

  • Specialty glasses, which constitute the leading market for rubidium, are used in fiber optics telecommunications systems and in night-vision devices.
  • The carbonate (Rb2CO3) is used as an additive to these types of glass, where it reduces electrical conductivity and improves stability and durability.
  • Rubidium-cesium-antimony coating is commonly applied to the photo-cathodes of photo-multiplier tubes, which are used in radiation detection devices, medical imaging equipment, and night-vision devices.

Properties of Rubidium

  • Compared with potassium and sodium, rubidium is relatively rare, with a crustal abundance of just 78 mg kg-1 (Fyfe 1999).
  • The Rb+ ion (ionic radius 152 pm) substitutes for K+ (138 pm) in mica such as muscovite and to a lesser extent in K-feldspar such as microcline and orthoclase, as well as rare minerals, such as lepidolite, carnallite, and pollucite, in which it replaces Cs.

Certain Facts About Rubidium

  • Used in fireworks to give purple-red color.
  • The metal along with strontium is used to date rocks, minerals, and meteorites radioactively.

Practise This Question

Column – I                                Column – II
A. Natural fibre                         P. Terylene
B. Synthetic fibre                      Q. Raincoats
C. Semisynthetic fibre              R. Wool
D. Rubber                                 S. Terry wool