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| Protactinium | Protactinium | Protaktinij | Protoattinio | Protactinium | ||||||||||||||||||||
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Pa Protactinium |
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- Protactinium was discovered by Otto Hahn (Germany) and Lise Meitner (Austria) in 1917. The origin of the name comes from the Greek word protos meaning first. It is very rare, silvery-white, extremely radioactive metal. Resists alkalis; reacts with oxygen and acids. Attacked by steam. Highly radiotoxic. Protactinium is extremely toxic and must be handled with great care.
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TRANSITION ELEMENT: ACTINIDE | |
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| Relative atomic mass: | 231.03588(2) | Electronic configuration: | [Rn] 5f2 6d1 7s2 |
| Formal oxidation number: | +4 +5 | Electronegativities: | 1.5 |
| Thermal conductivity: | 47 W m-1 K-1 | Electrical resistivity (20 °C): | 19.1 μΩcm |
| Atomic radius: | 156.1 pm | Standard state (20 °C): | solid |
| Density (g dm-3): | 15370 (pretp.) | Molar volume (cm3 mol-1): | 15.03 (pretp.) |
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THERMAL PROPERTIES | |
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| Melting point: | 1572 °C | Heat of fusion: | 16.7 kJ mol-1 |
| Boiling point: | - °C | Heat of vaporization: | 481 kJ mol-1 |
| Critical temperature: | 13727 °C | Heat of atomization: | 607 kJ mol-1 |
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IONIZATION ENERGIES AND ABUNDANCE | |
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| 1st ionization energy: | 568.30 kJ mol-1 | Abundance of element (air): | - ppm |
| 2nd ionization energy: | - kJ mol-1 | Abundance of element (Earth's crust): | 2E-12 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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231Pa | 231.035879(3) | * |
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MINERALS AND USES | |
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- Protactinium does not occur in nature. Found among fission products of uranium, thorium and plutonium.
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REDUCTION POTENTIALS | |
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Balanced half-reaction | Eo / V | Annotation |
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