Symbol

Fr

Atomic Number

87

Atomic Mass

223.0197

Family

Group 1 (Ia) Alkali Metal Pronunciation

FRAN-see-um

Overview

Francium is an alkali metal, a member of Group 1 (IA) in the periodic table. The periodic table is a chart that shows how chemical elements are related to each other.

Francium may be the rarest element found on the Earth's surface. Some experts believe that no more than 15 grams (less than an ounce) of the element exists in the Earth's crust. The element was discovered in 1939 by French chemist Marguerite Perey (1909-975). All isotopes of francium are radioactive.

Discovery and Naming

Francium was one of the last naturally-occurring elements to be discovered. Chemists had been searching for it since the development of the periodic table.

In the early 1900s, nearly all boxes on the periodic table had been filled. One element had been found to fit into each box. By the 1930s, only three...