Element 87
Francium (Fr)
Francium (Fr) is element 87 of the periodic table, a alkali metal in period 7, group 1 (s-block) with an atomic mass of 223 and is a solid at standard conditions.
At a glance
- Atomic number
- 87
- Symbol
- Fr
- Atomic mass
- 223 u
- Category
- Alkali metals
- Period
- 7
- Group
- 1
- Block
- s-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s1
- Shorthand configuration
- [Rn] 7s1
- Electrons per shell
- 2, 8, 18, 32, 18, 8, 1
- Oxidation states
- +1
Physical properties
- Melting point
- 300 K
- Boiling point
- 950 K
- Density
- 1.87 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 0.79
- Atomic radius
- 348 pm
- Covalent radius
- 260 pm
- Van der Waals radius
- 348 pm
- First ionization energy
- 380 kJ/mol
- Electron affinity
- 47 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Fr-223 | 223.01974 | — | Half-life 22 minutes |
Common uses
- Scientific research only
Discovery
- Year
- 1939
- Discovered by
- Marguerite Perey
- Country
- France