Francium: the essentials

Francium occurs as a result of α disintegration of actinium. Francium is found in uranium minerals, and can be made artificially by bombarding thorium with protons. It is the most unstable of the first 101 elements. The longest lived isotope, 223Fr, a daughter of 227Ac, has a half-life of 22 minutes. This is the only isotope of francium occurring in nature, but at most there is only 20-30 g of the element present in the earth's crust at any one time. No weighable quantity of the element has been prepared or isolated. There are about 20 known isotopes.

francium
This sample of uraninite contains some francium because of a steady-state decay chain. An estimate suggests there is about 10-20 grammes of francium (about 1 atom!) at any one time. Image adapted with permission from Prof James Marshall's (U. North Texas, USA) Walking Tour of the elements CD.

Francium: historical information

Francium was discovered by Marguerite Perey in 1939 at France. Origin of name: named after "France".

Francium was discovered in 1939 by Marguerite Perey of the Curie Institute in Paris, (France) but its existence was predicted by Mendeleev during the 1870's. Since its properties should track those of caesium rather closely, he called it eka-caesium. Marguerite Perey noticed an α decay product from actinium, now recognized as 22387Fr. This is the longest-lived isotope of actinium with a half life of about 22 minutes. She called the new element Francium after her country.

Francium around us Read more »

Francium has no biological role.

Very small amounts of francium are found in uranium ores. The longest lived isotope, 223Fr, a "daughter" of 227Ac, has a half-life of about 22 minutes. This is the only isotope of francium occurring in nature, but at most there is only 20-30 g of the element present in the earth's crust at any one time.

Abundances for cobalt in a number of different environments. More abundance data »
Location ppb by weight ppb by atoms Links
Universe (no data) (no data) Chemical elements abundance by weight in the universe on a miniature periodic table spark table
Crustal rocks (no data) (no data) Chemical elements abundance by weight in the earth's crust on a miniature periodic table spark table
Human (no data) ppb by weight (no data) atoms relative to C = 1000000 Chemical elements abundance by weight in humans on a miniature periodic table spark table

Physical properties Read more »

Heat properties Read more »

Crystal structure Read more »

The solid state structure of francium is: .

Francium: orbital properties Read more »

Francium atoms have 87 electrons and the shell structure is 2.8.18.32.18.8.1. The ground state electronic configuration of neutral Francium is [Rn].7s1 and the term symbol of Francium is 2S1/2.

Isolation

Isolation: francium is vanishingly rare and is found only as very small traces in some uranium minerals. It has never been isolated as the pure element. As it is so radioactive, any amount formed would decompose to other elements.

Actinium decays by β decay most of the time but about 1% of the decay is by α decay. The "daughter" element of this reaction, which used to be called actinium-K, is now recognized as 22387Fr - the longest-lived isotope of actinium with a half life of about 22 minutes.

Francium isotopes Read more »

Table. Stables isotopes of cobalt.
Isotope Mass
/Da
Natural
abund.
(atom %)
Nuclear
spin (I)
Nuclear
magnetic
moment (μ/μN)
nil

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