Difference between revisions of "Mendelevium"
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==Preparation== | ==Preparation== | ||
| − | Mendelevium was first prepared at the [[University of California Radiation Laboratory]] in Berkeley, California, in 1955 by the bombardment of {{Nuclide|A=253|Z=99}} targets (roughly 10<sup>9</sup> atoms) with 41 MeV [[α-particle]]s: just two atoms of the new element, later confirmed to be the ''A'' = 256 isotope, were produced per three-hour bombardment session. | + | Mendelevium was first prepared at the [[University of California Radiation Laboratory]] in Berkeley, California, in 1955 by the bombardment of {{Nuclide|A=253|Z=99}} targets (roughly 10<sup>9</sup> atoms) with 41 MeV [[α-particle]]s: just two atoms of the new element, later confirmed to be the ''A'' = 256 isotope, were produced per three-hour bombardment session. 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. A larger-scale preparation in 1958 demostrated a parent–daughter relationship between <sup>255</sup>101 and the previously-described <sup>255</sup>Fm. |
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| + | The preparation of mendelevium still follows the same principles as the first preparations, although production rates of about a million atoms per hour can now be obtained. | ||
==Notes and references== | ==Notes and references== | ||
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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. Its chemistry is typical of the late actinoids, with both the +3 and +2 oxidation states stable in aqueous solution.
Contents
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. 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. A larger-scale preparation in 1958 demostrated a parent–daughter relationship between 255101 and the previously-described 255Fm.
The preparation of mendelevium still follows the same principles as the first preparations, although production rates of about a million atoms per hour can now be obtained.
Notes and references
Notes
References
- ↑ Pauling, Linus The Nature of the Chemical Bond, 3rd ed.; Ithaca, NY, 1960; pp 88–95. ISBN 0-8014-0333-2.
- ↑ 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.
- ↑ 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.
- ↑ 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.
Further reading
- Hulet, E. K. Chemistry of the Heaviest Actinides: Fermium, Mendelevium, Nobelium, and Lawrencium. In Lanthanide and Actinide Chemistry and Spectroscopy; Edelstein, Norman M., Ed.; American Chemical Society: Washington, D.C., 1980; Chapter 12, pp 239–63. ACS Symposium Series, Vol. 131. ISBN 9780841205680. DOI: 10.1021/bk-1980-0131.ch012.
External links
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See also the corresponding article on Wikipedia. |
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