molybdenum

molybdenum
molybdenum
Symbol: Mo
Atomic number: 42
Atomic weight: 95.94
Silvery-white, hard metallic transition element. It is chemically unreactive and is not affected by most acids. It oxidizes at high temperatures. There are seven natural isotopes, and four radioisotopes, Mo-93 being the most stable with a half-life of 3500 years. Molybdenum is used in almost all high-strength steels, it has nuclear applications, and is a catalyst in petroleum refining. Discovered in 1778 by Carl Welhelm Scheele of Sweden. Impure metal was prepared in 1782 by Peter Jacob Hjelm. The name comes from the Greek word molybdos which means lead. Trace amounts of molybdenum are required for all known forms of life. All molybdenum compounds should be considered highly toxic, and will also cause severe birth defects.

Elements of periodic system. 2013.

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  • Molybdenum — Mol yb*de num, n. [NL.: cf. F. molybd[ e]ne. See {Molybdena}.] (Chem.) A rare element of the chromium group, occurring in nature in the minerals molybdenite and wulfenite, and when reduced obtained as a hard, silver white, difficulty fusible… …   The Collaborative International Dictionary of English

  • molybdenum — (n.) metallic element, 1816, from molybdena, used generally for lead like minerals, from Gk. molybdos lead, also black graphite, related to L. plumbum lead (see PLUMB (Cf. plumb) (n.)), and like it probably borrowed from a lost Mediterranean… …   Etymology dictionary

  • molybdenum — [mə lib′də nəm] n. [ModL: so named (1781) by K. W. Scheele (see SCHEELITE) after its isolation by P. J. Hjelm (1746 1813), Swed chemist < molybdaena, molybdenite, term used because of resemblance to lead ore < L molybdaena, lead, galena… …   English World dictionary

  • Molybdenum — niobium ← molybdenum → technetium Cr ↑ Mo ↓ W …   Wikipedia

  • molybdenum — /meuh lib deuh neuhm/, n. Chem. a silver white metallic element, used as an alloy with iron in making hard, high speed cutting tools. Symbol: Mo; at. wt.: 95.94; at. no.: 42; sp. gr.: 10.2. [1810 20; < NL, alter. of earlier molybdena < L… …   Universalium

  • molybdenum — noun Etymology: New Latin, from molybdena, a lead ore, molybdenite, molybdenum, from Latin molybdaena galena, from Greek molybdaina, from molybdos lead Date: 1814 a metallic element that resembles chromium and tungsten in many properties, is used …   New Collegiate Dictionary

  • molybdenum — A silvery white metallic element, atomic no. 42, atomic wt. 95.94; a bioelement found in a number of proteins ( e.g., xanthine oxidase). See m. target tube. [G. molybdaina, a piece of lead; a …   Medical dictionary

  • molybdenum-99 — A reactor produced radioisotope of molybdenum with a half life of 2.7476 days, used in radionuclide generators for the production of technetium 99m …   Medical dictionary

  • molybdenum — мед. молибден (molybdenum)  Микроэлемент.   Способствует метаболизму жиров и углеводов.   Жизненно важен для усвоения железа.   Участвует в производстве мочевой кислоты. см. тж микроэлементы …   Универсальный дополнительный практический толковый словарь И. Мостицкого

  • molybdenum — molibdenas statusas T sritis chemija apibrėžtis Cheminis elementas. simbolis( iai) Mo atitikmenys: lot. molybdaenum angl. molybdenum rus. молибден …   Chemijos terminų aiškinamasis žodynas

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