actinium

actinium
An element, atomic no. 89, atomic wt. 227.05; it possesses no stable isotopes and exists in nature only as a disintegration product of uranium and thorium. [G. aktis, a ray]

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ac·tin·i·um ak-'tin-ē-əm n a radioactive trivalent metallic element that resembles lanthanum in chemical properties and that is found esp. in pitchblende symbol Ac see ELEMENT (table)

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ac·tin·i·um (Ac) (ak-tinґe-əm) [Gr. aktis ray] a rare metallic chemical element occurring in the ores of uranium and having radioactive properties; atomic number 89, atomic weight 227.

Medical dictionary. 2011.

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  • ACTINIUM — L’existence dans la pechblende de l’actinium, élément radioactif de numéro atomique 89, fut établie en 1899 par André Louis Debierne, collaborateur de Pierre et Marie Curie qui venaient, un an auparavant, de découvrir, dans ce minerai d’uranium,… …   Encyclopédie Universelle

  • Actinium — (pronEng|ækˈtɪniəm) is a radioactive chemical element with the symbol Ac and atomic number 89, which was discovered in 1899, the earliest discovered of the radioactive elements.CharacteristicsActinium is a silvery, radioactive, metallic element.… …   Wikipedia

  • Actinium — Radium ← Actinium → Thorium La …   Wikipédia en Français

  • Actinium — Ac*tin i*um, n. [Gr. ?, ?, ray.] (Chem.) A supposed metal, said by Phipson to be contained in commercial zinc; so called because certain of its compounds are darkened by exposure to light. [1913 Webster] …   The Collaborative International Dictionary of English

  • actinium — ACTÍNIUM s.n. v. actiniu. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • actinium — Symbol: Ac Atomic number: 89 Atomic weight: (227) Silvery radioactive metallic element, belongs to group 3 of the periodic table. The most stable isotope, Ac 227, has a half life of 217 years. Ac 228 (half life of 6.13 hours) also occurs in… …   Elements of periodic system

  • actinium — (n.) radioactive element discovered in 1899, from Gk. actin , comb. form of aktis (gen. aktinos) ray, radiance (see ACTINO (Cf. actino )) + chemical suffix ium …   Etymology dictionary

  • actinium — [ak tin′ē əm] n. [ModL < ACTINO + IUM] a white, radioactive, metallic chemical element, the first member of the actinide series, found in pitchblende and other minerals or formed in reactors by the neutron irradiation of radium: symbol, Ac; at …   English World dictionary

  • actinium K — actinium K, the name originally given to element number 87 by its discoverer, who changed it to francium in 1947 …   Useful english dictionary

  • Actinium — Eigenschaften …   Deutsch Wikipedia

  • actinium — /ak tin ee euhm/, n. Chem. a radioactive silver white metallic element that glows blue in the dark, resembling the rare earths in chemical behavior and valence. Symbol: Ac; at. no.: 89; at. wt.: 227. [1900 05; ACTIN + IUM] * * * ▪ chemical… …   Universalium

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