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Actinium

Metal radioactivesolid
Symbol: Ac
Atomic number: 89
Atomic mass: (227.0278)
Group: Actinide
CAS-number: 7440-34-8

Physical data
Isotopes
Other info
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Physical data

Electronic data

Shells: 2, 8, 18, 32, 18, 9, 2
Orbitals: [Rn] 6d1 7s2
Electronegativity: --, 1.0
1. Ionization potential: 5.17 eV
2. Ionization potential: 12.126 eV
3. Ionization potential: -- eV
Oxidation states: 3
Electrical conductivity: --

Thermal data

Melting point: 1050 °C
Boiling point: 3200 °C ±300
Specific heat: -- J/gK
Heat of fusion: -- kJ/mol
Heat of vaporization: -- kJ/mol
Thermal conductivity: 0.12 W/cmK

Steric data

Atomic radius: -- Å
Ionic radius: -- Å
Covalent radius: -- Å
Atomic volume: 22.54 cm³/mol
Density (293 K): 10.07 g/cm³
Crystal structure: cubic face centered
cubic face centered

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
225Ac 0 225.023 0 10.0d α View
227Ac 0 227.028 3/2 21.77y β-, α View
228Ac 0 228 3 6.15h β- View

Other info

Name origin:Greek: akis, aktinos (ray).
Description:Heavy, silvery-white, very radioactive metal
Discovered by:André Debierne
Year:1899
Place:France
Sources:Extremely rare, found in all uranium ores. Usually obtained by treating radium with neutrons in a reactor.
Use(s):It has no significant commercial applications.