Metal radioactivesolid
Symbol: Fr
Atomic number: 87
Atomic mass: (223.0197)
Group: Alkali Metal
CAS-number: 7440-73-5

Physical data
Other info
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Physical data

Electronic data

Shells: 2, 8, 18, 32, 18, 8, 1
Orbitals: [Rn] 7s1
Electronegativity: 0.7, 0.9
1. Ionization potential: -- eV
2. Ionization potential: -- eV
3. Ionization potential: -- eV
Oxidation states: 1
Electrical conductivity: 0.03 10^6

Thermal data

Melting point: 27 °C
Boiling point: 677 °C
Specific heat: -- J/gK
Heat of fusion: -- kJ/mol
Heat of vaporization: -- kJ/mol
Thermal conductivity: 0.15 W/cmK

Steric data

Atomic radius: -- Å
Ionic radius: -- Å
Covalent radius: -- Å
Atomic volume: -- cm³/mol
Density (293 K): -- g/cm³
Crystal structure: cubic body centered
cubic body centered


NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
212Fr 0 211.996 5 20m EC, β+, α View
221Fr 0 221.014 5/2 4.80m α View
223Fr 0 223.02 3/2 21.8m β-, α View

Other info

Name origin:Named for France, the nation of its discovery.
Description:Highly rare and unstable, radioactive metal.
Discovered by:Marguerite Derey
Sources:Formed by decay of actinium. Chemical properties similar to cesium. Decays to radium or astatine.
Use(s):Since its isotopes have such short half-lives there are no commercially significant compounds of francium.