iridium

iridium
Symbol: Ir
Atomic number: 77
Atomic weight: 192.217
Very hard and brittle, silvery metallic transition element. It has a yellowish cast to it. Salts of iridium are highly colored. It is the most corrosion resistant metal known, not attacked by any acid, but is attacked by molten salts. There are two natural isotopes of iridium, and 4 radioisotopes, the most stable being Ir-192 with a half-life of 73.83 days. Ir-192 decays into platinum, while the other radioisotopes decay into osmium. Iridium is used in high temperature apparatus, electrical contacts, and as a hardening agent for platinum. Discovered in 1803 by Smithson Tennant in England. The name comes from the Greek word iris, which means rainbow. Iridium metal is generally non-toxic due to its relative unreactivity, but iridium compounds should be considered highly toxic.

Elements of periodic system. 2013.

  • Iridium — (pronEng|ɪˈrɪdiəm) is a chemical element that has the symbol Ir and atomic number 77. A very hard, brittle, silvery white transition metal of the platinum family, iridium is the second densest element and is the most corrosion resistant metal,… …   Wikipedia

  • iridium — [ iridjɔm ] n. m. • 1805; lat. iris, iridis « arc en ciel », à cause des couleurs variées qu offrent les combinaisons de ce métal ♦ Chim. Élément (Ir; no at. 77; m. at. 192), métal blanc très dur, cassant. L iridium s extrait de certains minerais …   Encyclopédie Universelle

  • Iridium-33 — Caractéristiques Organisation Iridium Domaine Télécommunications Masse 700 kg …   Wikipédia en Français

  • Iridium 33 — Caractéristiques Organisation Iridium Domaine Télécommunications Masse 700 kg Lancement 14 septembre 1997 Lanceur …   Wikipédia en Français

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  • iridium — i*rid i*um ([ i]*r[i^]d [i^]*[u^]m), n. [NL., fr. L. iris, iridis, the rainbow. So called from the iridescence of some of its solutions. See {Iris}.] (Chem.) A rare metallic element of atomic number 77, of the same group as platinum, which it… …   The Collaborative International Dictionary of English

  • Iridium [2] — Iridium Ir (Atomgew. 192,5, spez. Gew. 22,4), graues, hartes Metall der Platingruppe; Schmelzpunkt höher als der des Platins, ca. 2500° C. Es findet sich in Begleitung mit den übrigen Platinmetallen als seltenstes Element dieser Gruppe stets… …   Lexikon der gesamten Technik

  • Iridium — es el nombre de una constelación de 66 satélites de comunicaciones girando alrededor de la Tierra, en 11 órbitas longitudinales de 6 satélites cada una, diseñados por Motorola para proveer servicios de Telefonía Satelital Móvil (TSM) con… …   Enciclopedia Universal

  • iridium — IRÍDIUM s.n. v. iridiu. Trimis de gall, 13.09.2007. Sursa: DEX 98  IRÍDIUM s.n. v. iridiu. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • iridium — [ī rid′ē əm, i rid′ē əm] n. [ModL: so named (1804) by S. Tennant (1761 1815), Eng chemist < Gr iris (gen. iridos), IRIS, because its salts have varied colors; + IUM] a white, extremely dense, brittle, corrosion resistant chemical element, one… …   English World dictionary

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