|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|
- 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.
- 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.
- 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.