/thooh"lee euhm/, n. Chem.
a rare-earth metallic element found in the minerals euxenite, gadolinite, etc. Symbol: Tm; at. wt.: 168.934; at. no.: 69; sp. gr.: 9.32.
[1875-80; < NL; see THULE, -IUM]

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 (Tm), chemical element, rare-earth metal of the lanthanoid series of the periodic table. One of the rarest of the rare-earth elements, though more abundant than silver, thulium has few commercial uses. Natural thulium is wholly composed of the stable isotope thulium-169. Bombarded by neutrons, it becomes radioactive thulium-170 (128-day half-life), which ejects soft gamma radiation (0.084 million electron volts) resembling an X ray (X-ray). It is useful in small portable X-ray units suitable for photographing bony tissues and for examining thin-walled machine parts and has been used by archaeologists to examine markings and symbols on ancient metallic artifacts.

      Thulium was discovered (1879), along with holmium, by Per Teodor Cleve (Cleve, Per Teodor), who named the oxide thulia after an ancient name for Scandinavia. It is found in small amounts in such rare-earth minerals as xenotime and euxenite and in the products of nuclear fission. Commercial production involves ion exchange from the important mineral monazite (only about 0.007 percent thulium).

      Thulium can be prepared in the +2 oxidation state, as in the dark-coloured diiodide TmI2. The Tm2+ ion is not stable in water; it momentarily gives a violet-red colour before being oxidized to the predominant +3 state. Thulium in the +3 state forms a series of pale-green salts.

atomic number
atomic weight
melting point
1,545° C
boiling point
1,727° C
specific gravity
9.314 (25° C)
oxidation states
+2, +3
electronic config.
[Xe]4f 135d06s2

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Universalium. 2010.

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  • Thulium — (pronEng|ˈθjuːliəm) is a chemical element that has the symbol Tm and atomic number 69. A lanthanide element, thulium is the least abundant of the rare earths. It is an easily workable metal with a bright silvery gray luster and can be cut by a… …   Wikipedia

  • Thulium — Erbium ← Thulium → Ytterbium …   Wikipédia en Français

  • thulium — [ tyljɔm ] n. m. • 1904; lat. sc., nom donné par le chimiste suéd. Clève, du lat. Thule, gr. Thoulê, nom de la Scandinavie ♦ Chim. Élément atomique (Tm; no at. 69; m. at. 168,93), métal blanc argenté, du groupe des terres rares, utilisé dans la… …   Encyclopédie Universelle

  • Thulium — Thu li*um, n. [NL. See {Thule}.] (Chem.) A rare metallic element of uncertain properties and identity, said to have been found in the mineral gadolinite. [1913 Webster] [1913 Webster] …   The Collaborative International Dictionary of English

  • Thulium — Thu, Atomgew. 169,65, chemisches Element, in einigen norwegischen seltenen Mineralien vorkommend, so im Gadolinit, auch im Samarskit von Nordkarolina. Bujard …   Lexikon der gesamten Technik

  • thulium — Symbol: Tm Atomic number: 69 Atomic weight: 168.934 Soft grey metallic element that belongs to the lanthanoids. One natural isotope exists, Tm 169, and seventeen artificial isotopes have been produced. No known uses for the element. Discovered in …   Elements of periodic system

  • thulium — [tho͞o′lē əm, thyo͞o′lē əm] n. [ModL: so named (1886) by L. de Boisbaudran (see GADOLINIUM) < THULIA (from which it was isolated by Cleve in 1879) + IUM] a bright, silvery chemical element, one of the rare earth elements: symbol, Tm; at. no.,… …   English World dictionary

  • Thulium — Eigenschaften …   Deutsch Wikipedia

  • Thulium — Thu|li|um 〈n.; s; unz.; chem. 〉 chem. Element, Metall aus der Gruppe der Lanthanoide, Ordnungszahl 69 [nach dem nord. Sagenland Thule] * * * Thu|li|um [nach Thule, einem sagenhaften Land im fernen Norden; ↑ ium (1)], das; s; Symbol: Tm: chem.… …   Universal-Lexikon

  • Thulium — tulis statusas T sritis fizika atitikmenys: angl. thulium vok. Thulium, n rus. тулий, m pranc. thulium, m …   Fizikos terminų žodynas

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