Difference between revisions of "Americium"

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'''Americium''' (symbol: '''Am''') is a synthetic [[chemical element]], a member of the [[actinoid]] series.  
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'''Americium''' (symbol: '''Am''') is a synthetic [[chemical element]], a member of the [[actinoid]] series. It is produced in commercial [[nuclear reactor]]s, although it is not currently extracted during normal fuel reprocessing: nevertheless, kilogram quantities of [[Americium-241|<sup>241</sup>Am]] (''t''<sub>½</sub>&nbsp;= 432.2(7)&nbsp;a) and [[Americium-243|<sup>243</sup>Am]] (''t''<sub>½</sub>&nbsp;= 7.37(4){{e|3}}&nbsp;a) are available from the reprocessing of specialized fuel batches.<ref name="R&S"/> It has a number of small-scale commercial uses, particularly in domestic smoke alarms.
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Americium was first prepared in 1944 in the [[University of Chicago Metallurgical Laboratory]].<ref>{{citation | last1 = Ghiorso | first1 = A. | authorlink1 = Albert Ghioso | last2 = James | first2 = R. A. | last3 = Morgan | first3 = L. O. | last4 = Seaborg | first4 = G. T. | authorlink4 = Glenn T. Seaborg | title = Preparation of Transplutonium Isotopes by Neutron Irradiation | journal = Phys. Rev. | year = 1950 | volume = 78 | issue = 4 | pages = 472 | doi = 10.1103/PhysRev.78.472}}.</ref> It was named after the continent of America, by analogy with [[europium]], its [[lanthanoid]] homologue, named after the continent of Europe.
  
 
==Notes and references==
 
==Notes and references==

Latest revision as of 09:52, 24 April 2011

plutonium ← americium → curium
Eu
↑
Am
↓
—
Atomic properties
Atomic number 95
Electron configuration [Rn] 5f7 7s2
Physical properties[1][2][3]
Melting point 876(5) °C (1149(5) K)
Boiling point 2067 °C (2340 K)
Density 13.671 g cm−3
Electric resistivity 68 × 10−6 Ω cm
Chemical properties[4]
Electronegativity 1.3 (Pauling)
Ionization energies[5][6]
1st 5.9738(2) eV,
576.38(2) kJ mol−1
2nd 12.5 eV
1206 kJ mol−1
3rd 18.8 eV
1814 kJ mol−1
Atomic radii[2][7][8]
Covalent radius 180 pm
Metallic radius 173 pm
Ionic radius 85 pm (Am4+, Oh)
97.5 pm (Am3+, Oh)
121 pm (Am2+, Oh)
Thermodynamic properties[1][9]
Standard entropy 55 J K−1 mol−1
Enthalpy change of fusion 14.4 kJ mol−1
Enthalpy change of vaporization 230.2 kJ mol−1
Molar heat capacity (Cp) 25.5 J K−1 mol−1
Miscellaneous
CAS number 7440-35-9
EC number 231-144-4
Where appropriate, and unless otherwise stated, data are given for 100 kPa (1 bar) and 298.15 K (25 °C).
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Americium (symbol: Am) is a synthetic chemical element, a member of the actinoid series. It is produced in commercial nuclear reactors, although it is not currently extracted during normal fuel reprocessing: nevertheless, kilogram quantities of 241Am (t½ = 432.2(7) a) and 243Am (t½ = 7.37(4) × 103 a) are available from the reprocessing of specialized fuel batches.[1] It has a number of small-scale commercial uses, particularly in domestic smoke alarms.

Americium was first prepared in 1944 in the University of Chicago Metallurgical Laboratory.[10] It was named after the continent of America, by analogy with europium, its lanthanoid homologue, named after the continent of Europe.

Notes and references

Notes

References

  1. ↑ 1.0 1.1 1.2 Runde, Wolfgang H.; Schulz, Wallace W. Americium. 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. 3, Chapter 8, pp 1265–1395. doi:10.1007/1-4020-3598-5_8, <http://radchem.nevada.edu/classes/rdch710/files/americium.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. ↑ 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. ↑ Pauling, Linus The Nature of the Chemical Bond, 3rd ed.; Ithaca, NY, 1960. ISBN 0-8014-0333-2.
  5. ↑ Deissenberger, Rüdiger; Köhler, Stefan; Ames, Friedhelm; Eberhardt, Klaus; Erdmann, Nicole; Funk, Heike; Herrmann, Günter; Kluge, Heinz-Jürgen, et al. First Determination of the Ionization Potential of Americium and Curium. Angew. Chem., Int. Ed. Engl. 1995, 34 (7), 814–15. DOI: 10.1002/anie.199508141.
  6. ↑ Carlson, Thomas A.; Nestor, C. W., Jr.; Wasserman, Neil; Mcdowell, J. D. Calculated ionization potentials for multiply charged ions. At. Data Nucl. Data Tables 1970, 2, 63–99. DOI: 10.1016/S0092-640X(70)80005-5.
  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. ↑ Oetting, F. L.; Rand, M. H.; Ackerman, R. J. The Chemical Thermodynamics of Actinide Elements and Compounds; IAEA: Vienna, 1976; Vol. 1. ISBN 9201490763.
  10. ↑ Ghiorso, A.; James, R. A.; Morgan, L. O.; Seaborg, G. T. Preparation of Transplutonium Isotopes by Neutron Irradiation. Phys. Rev. 1950, 78 (4), 472. DOI: 10.1103/PhysRev.78.472.

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