What is "francium"

radioactive element, 1946, named by French physicist Marguerite Catherine Perey (1909-1975) who first identified it at the Curie Institute in Paris, from Latinized form of France + element ending -ium.

n. A metallic chemical element (''symbol'' Fr) with an atomic number of 87.

n. a radioactive element of the alkali-metal group discovered as a disintegration product of actinium [syn: Fr, atomic number 87]

Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka- caesium and actinium K. It is the second-least electronegative element, behind only caesium . Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron.

Bulk francium has never been viewed. Because of the general appearance of the other elements in its periodic table column, it is assumed that francium would appear as a highly reflective metal, if enough could be collected together to be viewed as a bulk solid or liquid. Obtaining such a sample is highly improbable, since the extreme heat of decay (the half-life of its longest-lived isotope is only 22 minutes) would immediately vaporize any viewable quantity of the element.

Francium was discovered by Marguerite Perey in France (from which the element takes its name) in 1939. It was the last element first discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays. As little as 20–30 g (one ounce) exists at any given time throughout the Earth's crust; the other isotopes (except for francium-221) are entirely synthetic. The largest amount produced in the laboratory was a cluster of more than 300,000 atoms.