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Definition: mendelevium from The Penguin Dictionary of Science

Symbol Md. The element with atomic number 101 and most stable isotope 258, named after the discoverer of the periodic table, Dmitri Ivanovich Mendeleyev (1834-1907). It is a ➤transuranium element and all isotopes are radioactive. Both Md2+ and Md3+ can be formed in aqueous solution.


Summary Article: mendelevium from The Columbia Encyclopedia

(mĕndəlāv'ēəm), artificially produced radioactive chemical element; symbol Md; at. no. 101; mass no. of most stable isotope 258; m.p. 827 degrees Celsius; b.p. and sp. gr. unknown; valence +1, +2, +3. Mendelevium is a metal of the actinide series in Group 3 of the periodic table. The ninth transuranium element to be discovered, it is named for the Russian chemist Dmitri Ivanovich Mendeleev. The symbol Mv was used at first, but it was changed to Md in 1963. Sixteen isotopes of mendelevium are known. Mendelevium-256 (half-life about 76 min) was the first isotope produced; it was detected in 1955 by Albert Ghiorso, Bernard G. Harvey, Gregory R. Choppin, Stanley G. Thompson, and Glenn T. Seaborg, who produced it one atom at a time by bombarding einsteinium-253 with alpha particles in a cyclotron at the Univ. of California at Berkeley. This technique of producing and detecting single atoms has become the standard for the discovery of the elements beyond mendelevium in the periodic table. Little is known of the properties of this element, since its isotopes are unstable and difficult to produce. Mendelevium-258 (the most stable isotope) has a half-life of 51.5 days; its synthesis (by bombarding einsteinium-255 with alpha particles) may make possible studies of the physical and chemical properties of the element.

The Columbia Encyclopedia, © Columbia University Press 2017

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