Francium (Fr)
Francium (Fr) is element 87 of the periodic table, an alkali metal in period 7 and group 1. It has no stable isotope and no standard atomic weight; 223 is the mass number of its longest-lived isotope. At room temperature it is a solid.
| Atomic number | 87 |
|---|---|
| Symbol | Fr |
| Standard atomic weight | [223] (mass number of the longest-lived isotope) |
| Molar mass | [223] g/mol |
| Category | Alkali metal |
| Group | 1 |
| Period | 7 |
| Block | s-block |
| Electron configuration | [Rn] 7s1 |
| Oxidation states | +1 |
| Electronegativity (Pauling) | 0.7 |
| Atomic radius (van der Waals) | 348 pm |
| First ionisation energy | 3.9 eV (376.3 kJ/mol) |
| Electron affinity | 0.47 eV |
| State at room temperature | Solid |
| Melting point | 300 K (26.85 °C) |
| Boiling point | — |
| Density | — |
| Discovered | 1939 |
Group 1
Calculate with Francium
Atomic weight: IUPAC CIAAW — no standard atomic weight; mass number in brackets. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.