Symbol

Rb

Atomic Number

37

Atomic Mass

85.4678

Family

Group 1 (Ia) Alkali Metal Pronunciation

roo-BID-ee-um

Overview

Rubidium is a soft, silvery metal. It is one of the most active chemical elements. Rubidium is a member of the alkali family. The alkali family consists of elements in Group 1 (IA) of the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. Other Group 1 (IA) elements include lithium, sodium, potassium, cesium, and francium. Rubidium was discovered in 1861 by German chemists Robert Bunsen (1811-99) and Gustav Kirchhoff (1824-87).

Rubidium is used to make atomic clocks. An atomic clock is a device for keeping very exact time. A radioactive isotope of rubidium is also used to measure the age of very old objects. In general, however, rubidium and its compounds have few practical uses.

Discovery and Naming

Rubidium is one of four elements discovered by spectroscopy...