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Francium (Fr)
Atomic number 87 · alkali
| Atomic number | 87 |
|---|---|
| Atomic mass | 223.0 u |
| Molar mass | 223.0 g/mol |
| Category | alkali |
| Group / period / block | 1 / 7 / s |
| Electron configuration | [Rn] 7s |
| Electrons per shell | 2, 8, 18, 32, 18, 8, 1 |
| Electronegativity (Pauling) | 0.7 |
| Density | 1.87 g/cm³ |
| First ionisation energy | 4.0727 eV |
| Melting point | 294.15 K (21.00 °C) |
| Common oxidation states | +1 |
Uses
Research only — extremely rare
Discovery
1939, Marguerite Derey