Francium

Francium is a chemical element with the symbol Fr and atomic number 87. It is an alkali metal in Group 1 of the periodic table and is extremely radioactive. All of its isotopes are unstable, and none occur naturally in any appreciable amount.

In nature, francium is extraordinarily scarce. It is produced only in trace amounts as a decay product within the uranium and thorium decay series, particularly from actinium-227. Because of its short half-lives, any francium formed quickly decays away, so the total quantity present on Earth at any time is tiny. It can be produced synthetically in very small quantities in particle accelerators or nuclear reactors for experimental study, but has no practical applications outside research.

Isotopes of francium are short-lived, with the most stable being francium-223, which has a half-life of about 22 minutes. Other isotopes decay in seconds or less. Chemically, francium is predicted to be highly reactive and electropositive, with properties similar to cesium and rubidium, but its extreme radioactivity and short half-lives limit direct observation of its chemistry. It would form Fr+ ions and react vigorously with water, but experiments are scarce. Due to its radioactivity, francium is handled only in specialized facilities and stored under appropriate precautions, typically under oil to limit reactivity.

Francium was discovered in 1939 by Marguerite Perey at the Curie Institute in Paris and was named after France. Its rarity and radioactivity mean it has no commercial use and is studied primarily for fundamental science.