Actinium

Metal

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

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Ra				Th

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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

Nuclide	Mass	Spin	Halflife	Decay mode	Decay tree
²²⁵Ac	225.023	0	10.0d	α	View
²²⁷Ac	227.028	3/2	21.77y	β-, α	View
²²⁸Ac	228	3	6.15h	β-	View

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.

Actinium

Physical data

Electronic data

Thermal data

Steric data

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