Difference between revisions of "Protactinium"

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|StdInChIkey = XLROVYAPLOFLNU-UHFFFAOYSA-N
 
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'''Protactinium''' (symbol: '''Pa''') is a member of the [[actinoid]] series of [[chemical element]]s.
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'''Protactinium''' (symbol: '''Pa''') is a [[chemical element]], a member of the [[actinoid]] series. Although all [[isotope]]s of protactinium are unstable, [[protactinium-231]] (''t''<sub>½</sub>&nbsp;= {{nowrap|3.276(11){{e|4}} a}})<ref name="NUBASE">{{NUBASE2003}}.</ref> is formed as a decay product of [[uranium-235]] (''t''<sub>½</sub>&nbsp;= {{nowrap|704(1){{e|6}} a}}) and so small amounts of protactinium are present in all samples of natural [[uranium]].
  
 
==Notes and references==
 
==Notes and references==

Revision as of 15:36, 14 April 2011

thorium ← protactinium → uranium
Pr
↑
Pa
↓
—
Atomic properties
Atomic number 91
Standard atomic weight 231.035 88(2)
Electron configuration [Rn] 5f2 6d1 7s2 [note 1]
Physical properties[1][2]
Melting point 1565(19) °C (1838 K)
Boiling point ca. 4227 °C (4500 K)
Density 15.37(8) g cm−3
Electric resistivity 19.1 × 10−6 Ω cm
Chemical properties[3]
Electronegativity 1.5 (Pauling)
Ionization energy[4]
5.89(12) eV
568(12) kJ mol−1
Atomic radii[1][5][6]
Covalent radius 200 pm
Metallic radius 163 pm
Ionic radius 92 pm (Pa5+, Oh)
Thermodynamic properties[2]
Enthalpy change of fusion 16.7 kJ mol−1
Enthalpy change of vaporization 481 kJ mol−1
Miscellaneous
CAS number 7440-13-3
Where appropriate, and unless otherwise stated, data are given for 100 kPa (1 bar) and 298.15 K (25 °C).
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Protactinium (symbol: Pa) is a chemical element, a member of the actinoid series. Although all isotopes of protactinium are unstable, protactinium-231 (t½ = 3.276(11) × 104 a)[7] is formed as a decay product of uranium-235 (t½ = 704(1) × 106 a) and so small amounts of protactinium are present in all samples of natural uranium.

Notes and references

Notes

  1. ↑ The configuration [Rn] 5f1 6d2 7s2 is given as a possible alternative in some textbooks.

References

  1. ↑ 1.0 1.1 Myasoedov, Boris F.; Kirby, H. W.; Tananaev, Ivan G. Protactinium. In The Chemistry of the Actinide and Transactinide Elements, 3rd ed.; Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean, Eds.; Springer: Dordrecht, the Netherlands, 2006; Vol. 1, Chapter 4, pp 161–252. doi:10.1007/1-4020-3598-5_4, <http://radchem.nevada.edu/classes/rdch710/files/protactinium.pdf>.
  2. ↑ 2.0 2.1 Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 1450–86. ISBN 0-08-022057-6.
  3. ↑ Pauling, Linus The Nature of the Chemical Bond, 3rd ed.; Ithaca, NY, 1960; pp 88–95. ISBN 0-8014-0333-2.
  4. ↑ Sugar, Jack Ionization energies of the neutral actinides. J. Chem. Phys. 1973, 59, 788–91. DOI: 10.1063/1.1680091. Sugar, Jack Revised ionization energies of the neutral actinides. J. Chem. Phys. 1974, 60, 4103. DOI: 10.1063/1.1680874.
  5. ↑ Cordero, Beatriz; Gómez, Verónica; Platero-Prats, Ana E.; Revés, Marc; Echeverría, Jorge; Cremades, Eduard; Barragán, Flavia; Alvarez, Santiago Covalent radii revisited. Dalton Trans. 2008 (5), 2832–38. DOI: 10.1039/b801115j.
  6. ↑ Shannon, R. D. Revised effective ionic radii and systematic studies of interatomic distances in halids and chalcogenides. Acta Crystallogr. A 1976, 32 (5), 751–67. DOI: 10.1107/S0567739476001551.
  7. ↑ Audi, G.; Bersillon, O.; Blachot, J.; Wapstra, A. H. The NUBASE evaluation of nuclear and decay properties. Nucl. Phys. A 2003, 729, 3–128. doi:10.1016/j.nuclphysa.2003.11.001, <http://amdc.in2p3.fr/nubase/Nubase2003.pdf>.

External links

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