actinium

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