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 nature. There are 22 other artificial isotopes, all radioactive and having very short half-lives. Chemistry similar to lanthanum. Used as a source of alpha particles. Discovered by A. Debierne in 1899.

Elements of periodic system. 2013.

  • 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 — (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 — 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

  • Actinium — Ac|ti|ni|um 〈n.; s; unz.; chem. 〉 = Aktinium * * * Ac|ti|ni|um [griech. aktís, Gen.: akti̅nos = Strahl; ↑ ium (1)], das; s; Symbol: Ac: radioaktives, natürlich vorkommendes chem. Element aus Gruppe 3 des Periodensystems, das oft als Anfangsglied… …   Universal-Lexikon