Francium is a chemical element with the symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 has a half-life of only 22 minutes. It is the second-most electropositive element, behind only cesium, and is the second rarest naturally occurring element. The isotopes of francium decay quickly into astatine, radium, and radon. The electronic structure of a Fr atom is [Rn] 7s1, and so the element is classed as an alkali metal.
|Atomic Mass||(233) g.mol -1|
|Discovered by||Marguerite Perey in 1939|
It was discovered by Marguerite Perey in France in 1939. It was the last element first discovered in nature, rather than by synthesis. Outside the laboratory, Fr 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.
Properties of Francium
- It is one of the most unstable of the naturally occurring elements: its longest-lived isotope, francium-223, has a half-life of only 22 minutes.
- It is the least founded metal on the planet earth and rarely found in nature. It is considered to be the second rarest metal discovered on the earth’s crust next to the Astatine.
- Fr is an element with chemical symbol Fr and atomic number 87 in the periodic table. It is produced both naturally and by artificial methods.
- Most probably, it is assumed that about 340-550 gms of this metal francium are found in the earth’s crust.
- Fr occurs on the decay of the alpha particles, which are found in the minerals of uranium.
- This metal has about 34 isotopes that are said to be occurring in nature. It has the only 1-valence electron.