Difference between revisions of "Mendelevium"

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|chem-ref = <ref>{{Pauling3rd|pages=88–95}}.</ref><ref group="note" name="est">The properties of mendelevium are only known through estimation and/or extrapolation.</ref>
 
|chem-ref = <ref>{{Pauling3rd|pages=88–95}}.</ref><ref group="note" name="est">The properties of mendelevium are only known through estimation and/or extrapolation.</ref>
 
|electronegativity = 1.3 (Pauling)
 
|electronegativity = 1.3 (Pauling)
−
|IE-ref =  
+
|IE-ref = <ref name="Sugar">{{citation | first = Jack | last = Sugar | title = Revised ionization energies of neutral actinides | journal = J. Chem. Phys. | volume = 60 | issue = 10 | year = 1974 | page = 4103 | doi = 10.1063/1.1680874}}.</ref><ref group="note" name="est"/>
−
|IE1 = ''see text''
+
|IE1 = 635 kJ mol<sup>−1</sup><br/>6.58 eV
 
|radius-ref = <ref>{{citation | last1 = David | first1 = F. | last2 = Samhoun | first2 = K. | last3 = Guillaumont | first3 = R. | last4 = Edelstein | first4 = N. | year = 1978 | title = Thermodynamic properties of 5''f'' elements | journal = J. Inorg. Nucl. Chem. | volume = 40 | issue = 1 | pages = 69–74 | doi = 10.1016/0022-1902(78)80309-1}}.</ref><ref>{{citation | last1 = Brüchle | first1 = W. | last2 = Schädel | first2 = M. | last3 = Scherer | first3 = U. W. | last4 = Kratz | first4 = J. V. | last5 =  Gregorich | first5 = K. E. | last6 = Lee | first6 = D. | last7 = Nurmia | first7 = M. | last8 = Chasteler | first8 = R. M. | last9 = Hall | first9 = H. L. | last10 = Henderson | first10 = R. A. | last11 = Hoffman | first11 = D. C. | year = 1988 | title = The hydration enthalpies of Md<sup>3+</sup> and Lr<sup>3+</sup> | journal =  Inorg. Chim. Acta | volume = 146 | issue = 2 | pages = 267–76 | doi = 10.1016/S0020-1693(00)80619-2}}.</ref><ref group="note" name="est"/>
 
|radius-ref = <ref>{{citation | last1 = David | first1 = F. | last2 = Samhoun | first2 = K. | last3 = Guillaumont | first3 = R. | last4 = Edelstein | first4 = N. | year = 1978 | title = Thermodynamic properties of 5''f'' elements | journal = J. Inorg. Nucl. Chem. | volume = 40 | issue = 1 | pages = 69–74 | doi = 10.1016/0022-1902(78)80309-1}}.</ref><ref>{{citation | last1 = Brüchle | first1 = W. | last2 = Schädel | first2 = M. | last3 = Scherer | first3 = U. W. | last4 = Kratz | first4 = J. V. | last5 =  Gregorich | first5 = K. E. | last6 = Lee | first6 = D. | last7 = Nurmia | first7 = M. | last8 = Chasteler | first8 = R. M. | last9 = Hall | first9 = H. L. | last10 = Henderson | first10 = R. A. | last11 = Hoffman | first11 = D. C. | year = 1988 | title = The hydration enthalpies of Md<sup>3+</sup> and Lr<sup>3+</sup> | journal =  Inorg. Chim. Acta | volume = 146 | issue = 2 | pages = 267–76 | doi = 10.1016/S0020-1693(00)80619-2}}.</ref><ref group="note" name="est"/>
 
|metallic-radius = 194(10) pm
 
|metallic-radius = 194(10) pm
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'''Mendelevium''' (symbol: '''Md''') is a synthetic [[chemical element]] and a member of the [[actinoid]] series. It cannot be formed by [[neutron]] bombardment in a nuclear reactor, but must instead be produced in [[particle accelerator]]s. Mendelevium cannot be produced in macroscopic quantities.
 
'''Mendelevium''' (symbol: '''Md''') is a synthetic [[chemical element]] and a member of the [[actinoid]] series. It cannot be formed by [[neutron]] bombardment in a nuclear reactor, but must instead be produced in [[particle accelerator]]s. Mendelevium cannot be produced in macroscopic quantities.
  
−
It was first prepared in 1955, and named after [[Dmitri Mendeleev]]. Its chemistry is typical of the late actinoids, with both the +3 and +2 [[oxidation state]]s stable in aqueous solution.
+
It was first prepared in 1955, and named after [[Dmitri Mendeleev]] in recognition of his development of the [[periodic table]]. Its chemistry is typical of the late actinoids, with both the +3 and +2 [[oxidation state]]s stable in aqueous solution.
  
 
==Preparation==
 
==Preparation==
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*{{citation | last = Hulet | first = E. K. | contribution = Chemistry of the Heaviest Actinides: Fermium, Mendelevium, Nobelium, and Lawrencium | title = Lanthanide and Actinide Chemistry and Spectroscopy | editor1-first = Norman M. | editor1-last = Edelstein | chapter = 12 | pages = 239–63 | year = 1980 | doi = 10.1021/bk-1980-0131.ch012 | id = ACS Symposium Series, Vol. 131 | publisher = American Chemical Society | location = Washington, D.C. | isbn = 9780841205680}}.
 
*{{citation | last = Hulet | first = E. K. | contribution = Chemistry of the Heaviest Actinides: Fermium, Mendelevium, Nobelium, and Lawrencium | title = Lanthanide and Actinide Chemistry and Spectroscopy | editor1-first = Norman M. | editor1-last = Edelstein | chapter = 12 | pages = 239–63 | year = 1980 | doi = 10.1021/bk-1980-0131.ch012 | id = ACS Symposium Series, Vol. 131 | publisher = American Chemical Society | location = Washington, D.C. | isbn = 9780841205680}}.
 
*{{citation | last = Seaborg | first = Glenn T. | authorlink = Glenn T. Seaborg | title = The transcalifornium elements | journal = J. Chem. Educ. | year = 1959 | volume = 36 | issue = 1 | pages = 38–44 | doi = 10.1021/ed036p38}}.
 
*{{citation | last = Seaborg | first = Glenn T. | authorlink = Glenn T. Seaborg | title = The transcalifornium elements | journal = J. Chem. Educ. | year = 1959 | volume = 36 | issue = 1 | pages = 38–44 | doi = 10.1021/ed036p38}}.
 +
*{{citation | last = Silva | first = Robert J. | contribution = Fermium, Mendelevium, Nobelium, and Lawrencium | 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 = 3 | publisher = Springer | location = Dordrecht, the Netherlands | chapter = 13 | pages = 1621–51 | url = http://radchem.nevada.edu/classes/rdch710/files/Fm%20to%20Lr.pdf | doi = 10.1007/1-4020-3598-5_13}}.
  
 
==External links==
 
==External links==

Revision as of 13:45, 5 April 2011

fermium ← mendelevium → nobelium
Tm
↑
Md
↓
–
Atomic properties
Atomic number 101
Electron configuration [Rn] 5f13 7s2
Chemical properties[1][note 1]
Electronegativity 1.3 (Pauling)
Ionization energy[2][note 1]
635 kJ mol−1
6.58 eV
Atomic radii[3][4][note 1]
Metallic radius 194(10) pm
Ionic radius 90 pm (Md3+)
Thermodynamic properties[5][note 1]
Enthalpy change of vaporization 134–142 kJ mol−1
Miscellaneous
CAS number 7440-11-1
Where appropriate, and unless otherwise stated, data are given for 100 kPa (1 bar) and 298.15 K (25 °C).
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Mendelevium (symbol: Md) is a synthetic chemical element and a member of the actinoid series. It cannot be formed by neutron bombardment in a nuclear reactor, but must instead be produced in particle accelerators. Mendelevium cannot be produced in macroscopic quantities.

It was first prepared in 1955, and named after Dmitri Mendeleev in recognition of his development of the periodic table. Its chemistry is typical of the late actinoids, with both the +3 and +2 oxidation states stable in aqueous solution.

Preparation

Mendelevium was first prepared at the University of California Radiation Laboratory in Berkeley, California, in 1955 by the bombardment of 25399Es targets (roughly 109 atoms) with 41 MeV α-particles: just two atoms of the new element, later confirmed to be the A = 256 isotope, were produced per three-hour bombardment session, and only seventeen atoms in total were detected.[6] The new element was identified by its elution time in ion-exchange chromatography: a spontaneous fission activity was observed both in the fermium fraction and in a fraction that eluted before the fermium, and this was taken to be a fermium daughter isotope produced by electron-capture decay of an isotope of element 101.[6] A larger-scale preparation in 1958 demostrated a parent–daughter relationship between 255101 and the previously-described 255Fm.[7]

The preparation of mendelevium still follows the same principles, although production rates of about a million atoms per hour can now be obtained.[8] The mendelevium atoms are collected on a thin metal film placed behind the einsteinium target (either 253Es or the longer-lived 254Es), or are carried in a stream of inert gas to a separate collection area. The collector foil is then dissolved in acid and the mendelevium is coprecipitated with lanthanum fluoride. The mendelevium is then separated from the lanthanum carrier and any lanthanoid fission products by ion-exchange chromatography using 10% aqueous ethanol saturated with hydrogen chloride as the eluant.[9] Final purification is acheived again by ion-exchange chromatography, this time using aqueous ammonium α-hydroxyisobutyrate as the eluant.[10]

Notes and references

Notes

  1. ↑ 1.0 1.1 1.2 1.3 The properties of mendelevium are only known through estimation and/or extrapolation.

References

  1. ↑ Pauling, Linus The Nature of the Chemical Bond, 3rd ed.; Ithaca, NY, 1960; pp 88–95. ISBN 0-8014-0333-2.
  2. ↑ Sugar, Jack Revised ionization energies of neutral actinides. J. Chem. Phys. 1974, 60 (10), 4103. DOI: 10.1063/1.1680874.
  3. ↑ David, F.; Samhoun, K.; Guillaumont, R.; Edelstein, N. Thermodynamic properties of 5f elements. J. Inorg. Nucl. Chem. 1978, 40 (1), 69–74. DOI: 10.1016/0022-1902(78)80309-1.
  4. ↑ Brüchle, W.; Schädel, M.; Scherer, U. W.; Kratz, J. V.; Gregorich, K. E.; Lee, D.; Nurmia, M.; Chasteler, R. M., et al. The hydration enthalpies of Md3+ and Lr3+. Inorg. Chim. Acta 1988, 146 (2), 267–76. DOI: 10.1016/S0020-1693(00)80619-2.
  5. ↑ Haire, R. G.; Gibson, J. K. Selected systematic properties and some recent investigations of actinide metals and alloys. J. Radioanal. Nucl. Chem. 1990, 143 (1), 35–51. DOI: 10.1007/BF02117545.
  6. ↑ 6.0 6.1 Ghiorso, A.; Harvey, B. G.; Choppin, G. R.; Thompson, S. G.; Seaborg, G. T. New Element Mendelevium, Atomic Number 101. Phys. Rev. 1955, 98 (5), 1518–19. DOI: 10.1103/PhysRev.98.1518.
  7. ↑ Phillips, L.; Gatti, R.; Chesne, A.; Muga, L.; Thompson, S. Discovery of a new Mendelevium Isotope. Phys. Rev. Lett. 1958, 1 (6), 215–21. DOI: 10.1103/PhysRevLett.1.215.
  8. ↑ Hulet, E. K.; Lougheed, R. W.; Brady, J. D.; Stone, R. E.; Coops, M. S. Mendelevium: Divalency and Other Chemical Properties. Science 1967, 158, 486–88. DOI: 10.1126/science.158.3800.486.
  9. ↑ Thompson, S. G.; Harvey, B. G.; Choppin, G. R.; Seaborg, G. T. Chemical Properties of Elements 99 and 100. J. Am. Chem. Soc. 1954, 76 (24), 6229–36. DOI: 10.1021/ja01653a004.
  10. ↑ Choppin, G. R.; Harvey, B. G.; Thompson, S. G. A new eluant for the separation of the actinide elements. J. Inorg. Nucl. Chem. 1956, 2 (1), 66–68. DOI: 10.1016/0022-1902(56)80105-X.

Further reading

External links

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