Difference between revisions of "Neptunium"

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{{Infobox element
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|name = neptunium
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|symbol = Np
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|left = [[uranium]]
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|right = [[plutonium]]
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|above = [[Promethium|Pm]]
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|below = —
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|atomic-number = 93
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|configuration = [Rn] 5f<sup>4</sup> 6d<sup>1</sup> 7s<sup>2</sup>
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|phys-ref = <ref name="Yoshida">{{citation | first1 = Zenko | last1 = Yoshida | first2 = Stephen G. | last2 = Johnson | first3 = Takaumi | last3 = Kimura | first4 = John R. | last4 = Krsul | contribution = Neptunium | title = The Chemistry of the Actinide and Transactinide Elements | editor1-first = Lester R. | editor1-last = Morss | editor2-first = Norman M. | editor2-last = Edelstein | editor3-first = Jean | editor3-last = Fuger | edition = 3rd | year = 2006 | volume = 2 | publisher = Springer | location = Dordrecht, the Netherlands | chapter = 6 | pages = 699–812 | url = http://radchem.nevada.edu/classes/rdch710/files/neptunium.pdf | doi = 10.1007/1-4020-3598-5_6}}.</ref><ref>{{Kaye&Laby | contribution = Electrical resistivities | chapter = 2.6.1 | accessdate = 2011-04-04 | url = http://www.kayelaby.npl.co.uk/general_physics/2_6/2_6_1.html}}.</ref>
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|melting-point = 639(3)&nbsp;°C (912(3)&nbsp;K)
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|boiling-point = 3900&nbsp;°C (4175&nbsp;K){{#tag:ref|The boiling point is extrapolated from valour pressure measurements.<ref name="E&M">{{citation | last1 = Eick | first1 = H. A. | last2 = Mulford | first2 = R. N. R. | title = Vapor Pressure of Neptunium | journal = J. Chem. Phys. | year = 1964 | volume = 41 | issue = 5 | pages = 1475–78 | doi = 10.1063/1.1726092}}.</ref>|group=note}}
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|density = 19.38 g cm<sup>−3</sup>
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|resistivity = 119.3{{e|−6}} Ω cm (100&nbsp;­°C)
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|chem-ref = <ref>{{Allred (1961)}}.</ref>
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|electronegativity = 1.36 (Pauling)
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|IE-ref = <ref>{{citation | first1 = S. | last1 = Köhler | first2 = R. | last2 = Deißenberger | first3 = K. | last3 = Eberhardt | first4 = N. | last4 = Erdmann | first5 = G. | last5 = Herrmann | first6 = G. | last6 = Huber | first7 = J. V. | last7 = Kratz | first8 = M. | last8 = Nunnemann | first9 = G. | last9 = Passler | first10 = P. M. | last10 = Rao | first11 = J. | last11 = Riegel | first12 = N. | last12 = Trautmann | first13 = K. | last13 = Wendt | title = Determination of the first ionization potential of actinide elements by resonance ionization mass spectroscopy | journal = Spectrochim. Acta, Part B | volume = 52 | issue = 6 | year = 1997 | pages = 717–26 | doi = 10.1016/S0584-8547(96)01670-9}}.</ref>
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|IE1 = 6.2655(2) eV,<br/>604.53(2) kJ mol<sup>−1</sup>
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|IE2 =
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|IE3 =
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|EA-ref =
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|EA1 =
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|thermo-ref = <ref name="E&M"/><ref name="Yoshida"/>
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|entropy = 50.5 J K<sup>−1</sup> mol<sup>−1</sup>
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|enthalpy-vaporization = 394(25) kJ mol<sup>−1</sup>
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|entropy-vaporization = 97(13) J K<sup>−1</sup> mol<sup>−1</sup>
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|enthalpy-atomization =
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|entropy-atomization =
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|enthalpy-fusion = 5.19 kJ mol<sup>−1</sup>
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|heat-capacity = 29.6 J K<sup>−1</sup> mol<sup>−1</sup>
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|radius-ref = <ref name="G&E">{{Greenwood&Earnshaw1st|pages=1450–86}}.</ref><ref>{{Cordero et al. (2008)}}.</ref><ref>{{Shannon (1976)}}.</ref>
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|metallic-radius = 155 pm
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|covalent-radius = 190 pm
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|ionic-radius = 86 pm (Np<sup>6+</sup>, ''O<sub>h</sub>'')<br/>101 pm (Np<sup>4+</sup>, ''O<sub>h</sub>'')
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|misc-ref =
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|CAS-number = 7439-99-8
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|EC-number = 231-108-8
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|StdInChIkey = LFNLGNPSGWYGGD-UHFFFAOYSA-N
 +
}}
 
'''Neptunium''' (symbol: '''Np''') is a [[chemical element]], a member of the [[actinoid]] series. All [[isotope]]s of neptunium are [[Radioactivity|unstable]], with [[Half-life|half-lives]] of less than about two million years:<ref>{{Nubase 2003}}.</ref> any neptunium that was present at the formation of the Solar System has long since decayed, although trace amounts of neptunium are naturally formed by the capture of [[neutron]]s by [[uranium-238]].<ref>{{citation | last1 = Peppard | first1 = D. F. | last2 = Mason | first2 = G. W. | last3 = Gray | first3 = P. R. | last4 = Mech | first4 = J. F. | title = Occurrence of the (4n + 1) Series in Nature | journal = J. Am. Chem. Soc. | year = 1952 | volume = 74 | pages = 6081–84 | doi = 10.1021/ja01143a074}}.</ref> Apart from these traces, neptunium is prepared artificially in [[nuclear reactor]]s.
 
'''Neptunium''' (symbol: '''Np''') is a [[chemical element]], a member of the [[actinoid]] series. All [[isotope]]s of neptunium are [[Radioactivity|unstable]], with [[Half-life|half-lives]] of less than about two million years:<ref>{{Nubase 2003}}.</ref> any neptunium that was present at the formation of the Solar System has long since decayed, although trace amounts of neptunium are naturally formed by the capture of [[neutron]]s by [[uranium-238]].<ref>{{citation | last1 = Peppard | first1 = D. F. | last2 = Mason | first2 = G. W. | last3 = Gray | first3 = P. R. | last4 = Mech | first4 = J. F. | title = Occurrence of the (4n + 1) Series in Nature | journal = J. Am. Chem. Soc. | year = 1952 | volume = 74 | pages = 6081–84 | doi = 10.1021/ja01143a074}}.</ref> Apart from these traces, neptunium is prepared artificially in [[nuclear reactor]]s.
  
−
Neptunium was first prepared in 1939  by [[Edwin McMillan]] at the [[University of California Radiation Laboratory]], by the neutron bombardment of [[uranium-238]].<ref>{{citation | last = McMillan | first = Edwin | authorlink = Edwin McMillan | title = Radioactive Recoils from Uranium Activated by Neutrons | journal = Phys. Rev. | year = 1939 | volume = 55 | issue = 5 | page = 510 | doi = 10.1103/PhysRev.55.510}}.</ref><ref>{{citation | last1 = McMillan | first1 = E. | authorlink1 = Edwin McMillan | last2 = Abelson | first2 = Philip Hauge | title = Radioactive Element 93 | journal = Phys. Rev. | year = 1940 | volume = 57 | issue = 12 | pages = 1185–86 | doi = 10.1103/PhysRev.57.1185.2}}.</ref> It was named after the planet Neptune, by analogy with uranium, named after the planet Uranus.
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Neptunium was first prepared in 1939  by [[Edwin McMillan]] at the [[University of California Radiation Laboratory]], by the neutron bombardment of uranium-238.<ref>{{citation | last = McMillan | first = Edwin | authorlink = Edwin McMillan | title = Radioactive Recoils from Uranium Activated by Neutrons | journal = Phys. Rev. | year = 1939 | volume = 55 | issue = 5 | page = 510 | doi = 10.1103/PhysRev.55.510}}.</ref><ref>{{citation | last1 = McMillan | first1 = Edwin | authorlink1 = Edwin McMillan | last2 = Abelson | first2 = Philip Hauge | title = Radioactive Element 93 | journal = Phys. Rev. | year = 1940 | volume = 57 | issue = 12 | pages = 1185–86 | doi = 10.1103/PhysRev.57.1185.2}}.</ref> It was named after the planet Neptune, by analogy with [[uranium]], named after the planet Uranus.
  
 
==Notes and references==
 
==Notes and references==
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===References===
 
===References===
 
{{reflist}}
 
{{reflist}}
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 +
===Further reading===
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*{{citation | last1 = Lemire | first1 = R. J. | last2 = Fuger | first2 = J. | last3 = Nitsche | first3 = H. | last4 = Potter | first4 = P. | last5 = Rand | first5 = M. H. | last6 = Rydberg | first6 = J. | last7 = Spahiu | first7 = K. | last8 = Sullivan | first8 = J. C. | last9 = Ullman | first9 = W. J. | last10 = Vitorge | first10 = P. | last11 = Wanner | first11 = H. | title = Chemical Thermodynamics of Neptunium and Plutonium | year = 2001 | publisher = Elsevier | location = Amsterdam | isbn = 044450379X}}.
  
 
==External links==
 
==External links==

Latest revision as of 04:40, 24 April 2011

uranium ← neptunium → plutonium
Pm
↑
Np
↓
—
Atomic properties
Atomic number 93
Electron configuration [Rn] 5f4 6d1 7s2
Physical properties[2][3]
Melting point 639(3) °C (912(3) K)
Boiling point 3900 °C (4175 K)[note 1]
Density 19.38 g cm−3
Electric resistivity 119.3 × 10−6 Ω cm (100 ­°C)
Chemical properties[4]
Electronegativity 1.36 (Pauling)
Ionization energy[5]
6.2655(2) eV,
604.53(2) kJ mol−1
Atomic radii[6][7][8]
Covalent radius 190 pm
Metallic radius 155 pm
Ionic radius 86 pm (Np6+, Oh)
101 pm (Np4+, Oh)
Thermodynamic properties[1][2]
Standard entropy 50.5 J K−1 mol−1
Enthalpy change of fusion 5.19 kJ mol−1
Enthalpy change of vaporization 394(25) kJ mol−1
Molar heat capacity (Cp) 29.6 J K−1 mol−1
Miscellaneous
CAS number 7439-99-8
EC number 231-108-8
Where appropriate, and unless otherwise stated, data are given for 100 kPa (1 bar) and 298.15 K (25 °C).
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Neptunium (symbol: Np) is a chemical element, a member of the actinoid series. All isotopes of neptunium are unstable, with half-lives of less than about two million years:[9] any neptunium that was present at the formation of the Solar System has long since decayed, although trace amounts of neptunium are naturally formed by the capture of neutrons by uranium-238.[10] Apart from these traces, neptunium is prepared artificially in nuclear reactors.

Neptunium was first prepared in 1939 by Edwin McMillan at the University of California Radiation Laboratory, by the neutron bombardment of uranium-238.[11][12] It was named after the planet Neptune, by analogy with uranium, named after the planet Uranus.

Notes and references

Notes

  1. ↑ The boiling point is extrapolated from valour pressure measurements.[1]

References

  1. ↑ 1.0 1.1 Eick, H. A.; Mulford, R. N. R. Vapor Pressure of Neptunium. J. Chem. Phys. 1964, 41 (5), 1475–78. DOI: 10.1063/1.1726092.
  2. ↑ 2.0 2.1 Yoshida, Zenko; Johnson, Stephen G.; Kimura, Takaumi; Krsul, John R. Neptunium. 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. 2, Chapter 6, pp 699–812. doi:10.1007/1-4020-3598-5_6, <http://radchem.nevada.edu/classes/rdch710/files/neptunium.pdf>.
  3. ↑ Electrical resistivities. In Kaye & Laby Tables of Physical & Chemical Constants, 16th ed., 1995; Chapter 2.6.1, <http://www.kayelaby.npl.co.uk/general_physics/2_6/2_6_1.html>. (accessed 4 April 2011).
  4. ↑ Allred, A. L. Electronegativity values from thermochemical data. J. Inorg. Nucl. Chem. 1961, 17 (3–4), 215–21. DOI: 10.1016/0022-1902(61)80142-5.
  5. ↑ Köhler, S.; Deißenberger, R.; Eberhardt, K.; Erdmann, N.; Herrmann, G.; Huber, G.; Kratz, J. V.; Nunnemann, M., et al. Determination of the first ionization potential of actinide elements by resonance ionization mass spectroscopy. Spectrochim. Acta, Part B 1997, 52 (6), 717–26. DOI: 10.1016/S0584-8547(96)01670-9.
  6. ↑ Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 1450–86. ISBN 0-08-022057-6.
  7. ↑ 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.
  8. ↑ 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.
  9. ↑ 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>.
  10. ↑ Peppard, D. F.; Mason, G. W.; Gray, P. R.; Mech, J. F. Occurrence of the (4n + 1) Series in Nature. J. Am. Chem. Soc. 1952, 74, 6081–84. DOI: 10.1021/ja01143a074.
  11. ↑ McMillan, Edwin Radioactive Recoils from Uranium Activated by Neutrons. Phys. Rev. 1939, 55 (5), 510. DOI: 10.1103/PhysRev.55.510.
  12. ↑ McMillan, Edwin; Abelson, Philip Hauge Radioactive Element 93. Phys. Rev. 1940, 57 (12), 1185–86. DOI: 10.1103/PhysRev.57.1185.2.

Further reading

  • Lemire, R. J.; Fuger, J.; Nitsche, H.; Potter, P.; Rand, M. H.; Rydberg, J.; Spahiu, K.; Sullivan, J. C., et al. Chemical Thermodynamics of Neptunium and Plutonium; Elsevier: Amsterdam, 2001. ISBN 044450379X.

External links

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