/hohl"mee euhm/, n. Chem.
a rare-earth, trivalent element found in gadolinite. Symbol: Ho; at. wt.: 164.930; at. no.: 67.
[ < NL (1879), equiv. to Holm(ia) Stockholm + -ium -IUM]

* * *

 (Ho), chemical element, rare-earth metal of the lanthanoid series of the periodic table, one of the most paramagnetic substances known. Among the least abundant of the rare-earth elements, holmium and its compounds have limited application except for research. Holmium has been used as a component of some electronic devices; the ion Ho3+ has been used as a catalyst for ortho-para hydrogen conversion; and the oxide has been used as a special refractory.

      Holmium was discovered (1878) spectroscopically by Jacques-Louis Soret and Marc Delafontaine and independently (1879) by Per Teodor Cleve (Cleve, Per Teodor), who separated it chemically from erbium and thulium. Cleve named the element for his native city of Stockholm, Sweden, its Latinized name being Holmia. Holmium occurs associated with other rare earths in the minerals xenotime, euxenite, and many others; it also occurs in the products of nuclear fission. The classical methods of separating and purifying the element were fractional crystallization and precipitation, but ion-exchange technology has now made available kilogram quantities of highly pure holmium oxide. The silvery metal is produced by thermoreduction of the anhydrous fluoride HoF3 with calcium. It is reactive and slowly attacked by oxygen and water. The one naturally occurring isotope, holmium-165, is stable; about two dozen radioactive artificial species are known.

      Holmium behaves as a typical rare earth; it forms a series of yellow-brown salts, many of which are obtained in solution by dissolving the oxide Ho2O3 in the appropriate acid.

atomic number
atomic weight
melting point
1,470° C
boiling point
2,720° C
specific gravity
8.781 (25° C)
oxidation state
electronic config.

* * *

Universalium. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Holmium — (pronEng|ˈhoʊlmiəm) is a chemical element with the symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a relatively soft and malleable silvery white metallic element, which is stable in dry air at room temperature. A rare… …   Wikipedia

  • Holmium — Dysprosium ← Holmium → Erbium …   Wikipédia en Français

  • holmium — [ ɔlmjɔm ] n. m. • 1880; de (Stock)holm et suff. ium ♦ Chim. Élément atomique (Ho; no at. 67; m. at. 164,93), métal du groupe des terres rares. ● holmium nom masculin (de Stockholm) Métal du groupe des terres rares. (Élément de symbole Ho, l… …   Encyclopédie Universelle

  • HOLMIUM — urbs Boeotiae. Eius meminit Hesiod. initio Theogoniae, sed ut fluvii, non civitatis, v. 6. Η῍ Ι῾πποκρην´ης, ἢ Ο᾿λμειοῦ ζαθέοιο. Aut in Hippocrene, aut in Olimio sacro. Strab. l. 9. p. 407. auctor est. Permessum autem et Holmium, seu fontes, seu… …   Hofmann J. Lexicon universale

  • holmium — Symbol: Ho Atomic number: 67 Atomic weight: 167.26 Relatively soft and malleable silvery white metallic element, which is stable in dry air at room temperature. It oxidizes in moist air and at high temperatures. It belongs to the lanthanoids. A… …   Elements of periodic system

  • holmium — rare earth element, named by French chemist Lecoq de Boisbaudran (1838 1912) in 1886, from holmia holmium oxide, a Modern Latin word coined by the earth s discoverer, Swedish chemist Per Teodor Cleve (1840 1905), in 1879 from Holmia, Latin name… …   Etymology dictionary

  • Holmium — Hol mi*um, n. [NL., from Stockholm.] (Chem.) A rare element of atomic number 67 said to be contained in gadolinite. Chemical symbol Ho. Atomic weight 164.93. Valence +3. It was detected by spectral absorption bands in 1878 by the Delafontaine and …   The Collaborative International Dictionary of English

  • Holmĭum — Holmĭum, Ho, ein unsicheres chemisches Element, dessen Oxyd aus Erbinerde abgeschieden wurde …   Meyers Großes Konversations-Lexikon

  • holmium — [hōl′mē əm] n. [ModL < earlier holmia, so named (1879) by P. T. Cleve (see CLEVEITE), its second discoverer (first was L. Soret, Fr chemist, in 1878), after Holmia, Latinized name of STOCKHOLM, his native city + IUM] a trivalent, silvery… …   English World dictionary

  • Holmium — Eigenschaften …   Deutsch Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”