Actinium
Chemical, physical and material properties and data of the chemical element Actinium.
General Information about Actinium
Regular nameActiniumChemical symbolAcOther namesElement 89Systematic nameHistorical namesEmaniumName meaning, originGreek: aktinos - ray, for radiation, radioactivityDiscovery (year)(1899) - Friedrich Oskar Giesel (discoverer, 1st isolation); André Louis DebierneOccurencePosition in the PSEGroup membership
Atomar Properties of Actinium
Atomic number Z89 = number of protonsStandard Atomic Weight227.027752408
Electron configuration of Actinium
| 1s | 2s | 2p | 3s | 3p | 3d | 4s | 4p | 4d | 4f | 5s | 5p | 5d | 5f | 6s | 6p | 6d | 6f | 7s | 7p |
|---|
| 2 | 2 | 6 | 2 | 6 | 10 | 2 | 6 | 10 | 14 | 2 | 6 | 10 | | 2 | 6 | 1 | | 2 | |
Abbreviated form: [Rn] 6d1 7s2 .
Ionization Energies of Actinium
The following table lists the ionization energies IE (ionization potentials); the IE is the energy required in electron volts (eV) per atom to separate a given electron from an Actinium atom.
Isotopic Data of Actinium
An overview of the nuclides as well as the isotopic data and properties are listed on the following page: Actinium isotopes.
Chemistry of Actinium
Oxidation states+ 3. (+ 2)Electronegativity1.1 (Pauling original)
1.10 (Pauling)Electron affinity0.35 eV
33.77 kJ mol-1
Standard Electrode Potential
| E0 (V) | Symbol | Nox | Name Ox.
Name Red. | Ox.
Red. | e- |
|---|
| -2.20 | Ac | + III
0 | Actinium(III) cation
Actinium | Ac3+
⇄ Ac (s) | + 3 e- |
Material and Physical Properties
Melting point1050 °CEnthalpy of fusion (molar)14 kJ mol-1Boiling point3198 °CEnthalpy of vaporization293 kJ mol-1Density10.07 g cm-3 (25°C)
External Data, Identifiers
CAS registry number7440-34-8InChI =1S/AcInChIKeyQQINRWTZWGJFDB-UHFFFAOYSA-NPubChem ID23965
Last update: 2022-12-08
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