Atomic number 87
Francium
Alkali metal
No photo: here’s why
Francium is wildly unstable: its longest-lived form lasts about 22 minutes. It exists only as a fleeting step in uranium's decay chain, so although new atoms keep forming in trace amounts, it has never been gathered into a visible piece.
Quick facts
- Atomic mass
- 223.00
- Group
- 1
- Period
- 7
- State (STP)
- solid
- Electronegativity
- 0.70
- Common ox. states
- +1
Properties
[Rn] 7s¹
- Ionization energy
- 380.0 kJ/mol
- Electron affinity
- 46.9 kJ/mol
- Melting point
- 300.00 K (26.9 °C)
- Boiling point
- 950.00 K (676.9 °C)
How dangerous is it?
So rare and short-lived that only a few atoms exist at any moment, and they decay almost instantly. No weighable amount has ever been collected.
- RadioactiveImmediate
It is intensely radioactive and decays within moments of forming, so its energy is released almost as fast as it appears. (it exists only as a handful of short-lived atoms, never a bulk sample)
Studied only as a few atoms at a time inside specialized research equipment.
How it bonds
Francium is the second-rarest naturally occurring element (after astatine). Predicted to be even more reactive than cesium, but every isotope decays so fast (Fr-223 has a 22-minute half-life) that no one has ever seen more than a few thousand atoms at a time.
