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| Actinium | Actinium | Aktinij | Attinio | Actinium | ||||||||||||||||||||
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Ac Actinium |
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- Actinium was discovered by André Debierne (France) in 1899. The origin of the name comes from the Greek word aktinos meaning ray. It is heavy, silvery-white, very radioactive metal. Reacts with water. Glows in the dark.
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TRANSITION ELEMENT: SCANDIUM GROUP | |
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| Relative atomic mass: | [227] | Electronic configuration: | [Rn] 6d1 7s2 |
| Formal oxidation number: | +3 | Electronegativities: | 1.1 |
| Thermal conductivity: | 12 W m-1 K-1 | Electrical resistivity (20 °C): | - μΩcm |
| Atomic radius: | 188 pm | Standard state (20 °C): | solid |
| Density (g dm-3): | 10060 (293 K) | Molar volume (cm3 mol-1): | 22.56 (293 K) |
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THERMAL PROPERTIES | |
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| Melting point: | 1051 °C | Heat of fusion: | - kJ mol-1 |
| Boiling point: | 3198 °C | Heat of vaporization: | - kJ mol-1 |
| Critical temperature: | 15997 °C | Heat of atomization: | 406 kJ mol-1 |
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IONIZATION ENERGIES AND ABUNDANCE | |
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| 1st ionization energy: | 498.83 kJ mol-1 | Abundance of element (air): | - ppm |
| 2nd ionization energy: | 1167.48 kJ mol-1 | Abundance of element (Earth's crust): | - ppm |
| 3rd ionization energy: | - kJ mol-1 | Abundance of element (oceans): | - ppm |
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ISOTOPES | |
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Isotopes | Relative atomic mass | Abundance (%) |
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227Ac | 227.027747(3) | * |
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MINERALS AND USES | |
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- Actinium is extremely rare, found in all uranium ores. Usually obtained by treating radium with neutrons in a reactor.
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REDUCTION POTENTIALS | |
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Balanced half-reaction | Eo / V | Annotation |
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