Difference between revisions of "Polonium"

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'''Polonium''' (symbol: '''Po''') is a [[chemical element]], one of the [[chalcogen]]s. It is a silvery-white metal with a unique [[simple cubic structure]],<ref name="G&E"/> although it is rare that polonium or its compounds are encountered in weighable quantities.
 
'''Polonium''' (symbol: '''Po''') is a [[chemical element]], one of the [[chalcogen]]s. It is a silvery-white metal with a unique [[simple cubic structure]],<ref name="G&E"/> although it is rare that polonium or its compounds are encountered in weighable quantities.
  
Polonium has no stable isotopes, and the metal and all its compounds are intensely radioactive. The power output due to the radioactive decay of [[polonium-210]] is about {{nowrap|140&nbsp;W g<sup>−1</sup>}}, which leads to considerable self-heating and which complicates the investigation of its properties with macroscopic quantities.<ref name="G&E"/>
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Polonium has no stable isotopes, and the metal and all its compounds are intensely [[Radioactivity|radioactive]]. The power output due to the radioactive decay of [[polonium-210]] is about {{nowrap|140&nbsp;W g<sup>−1</sup>}}, which leads to considerable self-heating and which complicates the investigation of its properties with macroscopic quantities.<ref name="G&E"/>
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==History==
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Polonium was discovered in 1898 by [[Marie Curie]] while she was investigating the radioactivity of [[pitchblende]]. The isolation of miligram quantities of polonium required the processing of over 15&nbsp;tonnes of ore, and earned Marie Curie the [[Nobel Prize for Chemistry]] in 1911. The element was named after Curie's native Poland.<ref name="G&E"/>
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==Occurrence and production==
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The only naturally ocurring isotope of polonium is [[polonium-210]] (''t''<sub>½</sub>&nbsp;= 138.38&nbsp;days), the penultimate member of the [[radium decay series]]. It occurs in [[uranium]] ores at about 0.1&nbsp;mg per tonne of ore (a mass fraction of about 10<sup>−10</sup>). The overall abundance of polonium in crustal rocks can be estimated at about 3{{e|−10}}&nbsp;ppm.<ref name="G&E"/>
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Extraction of polonium from natural sources is impractical, and it is produced commercially by the [[neutron]] irradiation of [[bismuth]] in a nuclear reactor.<ref name="G&E"/>
  
 
==Notes and references==
 
==Notes and references==

Revision as of 15:40, 23 May 2010

bismuthpoloniumastatine
Te

Po

Uuh
Atomic properties
Atomic number 84
Standard atomic weight 209.983[note 1]
Electron configuration [Xe] 6s2 4f14 5d10 6p4
Physical properties[1]
Melting point 254 °C
Boiling point 962 °C
Density 9.142 g cm−3 (α-form)
Ionization energy[2]
813.0 kJ mol−1
Miscellaneous
CAS number 7440-08-6
Where appropriate, and unless otherwise stated, data are given for 100 kPa (1 bar) and 298.15 K (25 °C).

Polonium (symbol: Po) is a chemical element, one of the chalcogens. It is a silvery-white metal with a unique simple cubic structure,[1] although it is rare that polonium or its compounds are encountered in weighable quantities.

Polonium has no stable isotopes, and the metal and all its compounds are intensely radioactive. The power output due to the radioactive decay of polonium-210 is about 140 W g−1, which leads to considerable self-heating and which complicates the investigation of its properties with macroscopic quantities.[1]

History

Polonium was discovered in 1898 by Marie Curie while she was investigating the radioactivity of pitchblende. The isolation of miligram quantities of polonium required the processing of over 15 tonnes of ore, and earned Marie Curie the Nobel Prize for Chemistry in 1911. The element was named after Curie's native Poland.[1]

Occurrence and production

The only naturally ocurring isotope of polonium is polonium-210 (t½ = 138.38 days), the penultimate member of the radium decay series. It occurs in uranium ores at about 0.1 mg per tonne of ore (a mass fraction of about 10−10). The overall abundance of polonium in crustal rocks can be estimated at about 3 × 10−10 ppm.[1]

Extraction of polonium from natural sources is impractical, and it is produced commercially by the neutron irradiation of bismuth in a nuclear reactor.[1]

Notes and references

Notes

  1. Atomic weight of polonium-210, which is by far the most commonly encountered isotope.

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 882–919. ISBN 0-08-022057-6.
  2. CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p E-65. ISBN 0-8493-0462-8.

Further reading

External links

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