HHomeBackground Color:He
LiBeActinium Main PageBlack White GrayBCNOFNe
NaMgActinium Pictures PageAlSiPSClAr
KCaActinium Isotope DataScTiVCrMnFeCoNiCuZnGaGeAsSeBrKr
RbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXe
CsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRn
FrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Technical data for Actinium

Click any property name to see plots of that property for all the elements.

Overview
NameActinium
SymbolAc
Atomic Number89
Atomic Weight227[note]
Density10.07 g/cm3
Melting Point1050 °C
Boiling Point3200 °C

Thermal properties
PhaseSolid
Melting Point1050 °C
Boiling Point3200 °C
Absolute Melting Point1323 K
Absolute Boiling Point3473 K
Critical PressureN/A
Critical TemperatureN/A
Heat of Fusion14 kJ/mol
Heat of Vaporization400 kJ/mol
Specific Heat120 J/(kg K)[note]
Adiabatic IndexN/A
Neel PointN/A
Thermal Conductivity12 W/(m K)
Thermal ExpansionN/A

Bulk physical properties
Density10.07 g/cm3
Density (Liquid)N/A
Molar Volume0.00002254220456802
Brinell HardnessN/A
Mohs HardnessN/A
Vickers HardnessN/A
Bulk ModulusN/A
Shear ModulusN/A
Young ModulusN/A
Poisson RatioN/A
Refractive IndexN/A
Speed of SoundN/A
Thermal Conductivity12 W/(m K)
Thermal ExpansionN/A

Reactivity
Valence3
Electronegativity1.1
ElectronAffinityN/A
Ionization Energies
499, 1170 kJ/mol

Health and Safety
DOT Hazard ClassN/A
DOT NumbersN/A
RTECS NumberN/A
NFPA LabelN/A

Classifications
Alternate NamesNone
Names of AllotropesNone
Blockf
GroupN/A
Period7
SeriesActinide
Electron Configuration[Rn]7s26d1
ColorSilver
Discovery
1899 in France
Gas phaseN/A
CAS NumberCAS7440-34-8
CID NumberN/A
RTECS NumberN/A

Electrical properties
Electrical TypeN/A
Electrical ConductivityN/A
ResistivityN/A
Superconducting PointN/A

Magnetic properties
Magnetic TypeN/A
Curie PointN/A
Mass Magnetic SusceptibilityN/A
Molar Magnetic SusceptibilityN/A
Volume Magnetic SusceptibilityN/A

Abundances
% in UniverseN/A
% in Sun0%
% in MeteoritesN/A
% in Earth's CrustN/A
% in OceansN/A
% in Humans0%

Atomic dimensions and structure
Atomic RadiusN/A
Covalent Radius215 pm
Van der Waals RadiusN/A
Crystal StructureFace-centered Cubic
Lattice Angles
π/2, π/2, π/2
Lattice Constants
567, 567, 567 pm
Space Group NameFm_ 3m
Space Group Number225

Nuclear Properties
Half-Life21.78652968037 y
Lifetime31.43106291223 y
Decay ModeBetaDecay
Quantum Numbers2D3/2
Neutron Cross Section880
Neutron Mass Absorption0.078
Known Isotopes
206Ac, 207Ac, 208Ac, 209Ac, 210Ac, 211Ac, 212Ac, 213Ac, 214Ac, 215Ac, 216Ac, 217Ac, 218Ac, 219Ac, 220Ac, 221Ac, 222Ac, 223Ac, 224Ac, 225Ac, 226Ac, 227Ac, 228Ac, 229Ac, 230Ac, 231Ac, 232Ac, 233Ac, 234Ac, 235Ac, 236Ac
Stable Isotopes
None
Isotopic Abundances


Notes on the properties of Actinium:

Atomic Mass: Atomic mass number given for longest lived isotope.

Specific Heat: Value given for solid phase.

Up to date, curated data provided by Mathematica's ElementData function from Wolfram Research, Inc.

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