mendelevium

mendelevium
/men'dl ee"vee euhm/, n. Chem., Physics.
a transuranic element. Symbol: Md, Mv; at. no.: 101.
[1950-55; named after D. I. MENDELEEV; see -IUM]

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 (Md),  
 synthetic chemical element of the actinoid series of the periodic table, atomic number 101. It was the first element to be synthesized and discovered one atom at a time. Not occurring in nature, mendelevium (as the isotope mendelevium-256) was discovered (1955) by Albert Ghiorso, Bernard G. Harvey, Gregory R. Choppin, Stanley G. Thompson, and Glenn T. Seaborg at the University of California, Berkeley, as a product resulting from the helium-ion bombardment of a minute quantity (1,000,000,000 atoms) of einsteinium-253 (atomic number 99).

      In about a dozen repetitions of the experiment, the team of scientists produced 17 atoms of mendelevium, which were identified by the ion-exchange adsorption–elution method (mendelevium behaved like its rare-earth homologue thulium). Other isotopes of mendelevium, all radioactive, have been discovered. The stablest is mendelevium-258 (two-month half-life). Studied by means of radioactive tracer techniques, mendelevium exhibits a predominant +3 oxidation state, as would be expected by its position in the actinoid series; a moderately stable +2 oxidation state is also known.

atomic number
101
stablest isotope
258
oxidation states
+2, +3
electronic config.
[Rn]5f137s2

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Universalium. 2010.

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  • mendelevium — men*de*le vi*um (m[e^]n*d[e^]*l[=e] v[=e]*[u^]/m), a. [From Dmitri Mendeleyev, discoverer of the periodic law.] (Chem.) an unstable radioactive element discovered in 1955 and produced artificially only in very small quantities; symbol Md (also… …   The Collaborative International Dictionary of English

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  • mendelevium — 1955, Modern Latin, in honor of Dmitri Ivanovich Mendeleev …   Etymology dictionary

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