Francium (Fr)
"The Fleeting Phantom, the most unstable hero of the first 101, disappearing in a flash of energy."
A memorable persona to anchor Fr in your mind.
1.87
Grams per cm³
21
Celsius (°C)
348
Radius (pm)
Daily Life Link
Francium has no everyday connection due to its extreme instability.
Discovery & History
Year Discovered
1939
Discovered By
Marguerite Perey
Origin of Name
"Francium is named after France."
Technical Properties
Atomic Mass
[223] u
Standard State
solid
Boiling Point
650°C
Electron Configuration
[Rn] 7s1
1st Ionization Energy
3.9 eV
Electron Affinity
N/A
Oxidation States
"Francium is a highly radioactive and reactive alkali metal."
Did You Know?
It is the second rarest element in nature, after astatine. It is estimated that there are only about 20-30 grams of it in the entire Earth's crust at any time.
It is the most unstable of the first 101 elements; its most stable isotope has a half-life of only 22 minutes.
It was the last naturally occurring element to be discovered, identified in 1939 by Marguerite Perey in Paris. She named it after her home country, France.
As an alkali metal, it is predicted to be the most reactive metal on the periodic table, though it's too unstable to ever gather enough to test this.