Fr
Francium
Element 87 · 223.01973 u
Francium is the most unstable naturally occurring element with a half-life of only 22 minutes.
Physical Properties
| Atomic Mass | 223.01973 u |
| Density | 1.87 g/cm³ |
| Melting Point | 300.0 K |
| Boiling Point | 950.0 K |
| Appearance | Likely silvery metallic |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 0.7 (Pauling) |
| 1st Ionization Energy | 380.0 kJ/mol |
| Electron Affinity | 46.89 kJ/mol |
| Oxidation States | +1 |
Atomic Properties
| Electron Configuration | [Rn] 7s1 |
| Atomic Radius | 260.0 pm |
| Covalent Radius | 260.0 pm |
| Van der Waals Radius | 348.0 pm |
Discovery
| Discovered By | Marguerite Perey |
| Discovery Year | 1939 |
| Location | Paris, France |
| Named After | Named after France |
About Francium
Francium is an extremely radioactive alkali metal. Its longest-lived isotope has a half-life of only 22 minutes. It has never been produced in visible quantities and was the last element discovered in nature.
Uses & Applications
No commercial applications. Used only in basic spectroscopy research.
Fun Fact
At most about 30 grams of francium exist in the entire Earth's crust, and the largest amount collected was about 300,000 atoms.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 221 | - | 4.9 minutes | No |
| 223 | - | 22.0 minutes | No |
Electron Configuration
[Rn] 7s1