scandium

/skan"dee euhm/, n. Chem.
a rare, trivalent, metallic element obtained from thortveitite. Symbol: Sc; at. wt.: 44.956; at. no.: 21; sp. gr.: 3.0.
[1875-80; < NL; see SCANDIA, -IUM]

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 (Sc), chemical element, rare-earth metal of transition Group IIIb of the periodic table. Scandium is a silvery-white, rather soft metal. After Dmitry Ivanovich Mendeleyev predicted (1871) its existence, tentatively calling it ekaboron, Lars Fredrik Nilson discovered (1879) its oxide, scandia, in the rare-earth minerals gadolinite and euxenite, and Per Teodor Cleve (Cleve, Per Teodor) (later in 1879) identified scandium with the hypothetical ekaboron.

      Scandium is found in small proportions in many of the heavy rare-earth ores of Scandinavia and elsewhere and in many tin and tungsten ores; it also occurs in the products of nuclear fission. The cosmic abundance of scandium is relatively high. Although it is only about the 50th most abundant element on Earth, it is about the 23rd most abundant element in the Sun.

      Scandium is easily separated from the other rare earths by precipitation of the very insoluble potassium scandium sulfate or by extraction of scandium thiocyanate by diethyl ether. The metal itself was first prepared (1938) by the electrolysis of potassium, lithium, and scandium chlorides in a eutectic mixture (i.e., a mixture having the lowest melting point possible with those components). Scandium is now produced on a small scale mostly as a by-product of uranium extraction from the mineral davidite, which contains about 0.02 percent scandium oxide. Very few uses of this unusual metal have been developed. Its low density and high melting point suggest applications as an alloying agent for devices requiring lightweight metals. After irradiation in an atomic pile, scandium emits strong gamma radiation with an 85-day half-life, for which it could be used in radiotherapy.

      The chemistry of scandium bears a closer resemblance to that of the other rare-earth elements of oxidation state +3 than to that of aluminum or titanium. Some of its behaviour, however, is atypical of the rare earths because of its significantly smaller ionic radius (0.73 angstrom [Å]) as compared with the rare-earth average (0.96 Å). For this reason the Sc3+ ion is a relatively strong acid and has a much greater tendency to form complex ions. The Sc3+ ion is paramagnetic. Natural scandium is wholly composed of the stable isotope scandium-45.

atomic number
21
atomic weight
44.956
melting point
1,539° C
boiling point
2,832° C
specific gravity
2.989 (25° C)
oxidation state
+3
electronic config.
[Ar]3d14s2

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Universalium. 2010.

Look at other dictionaries:

  • Scandium — (pronEng|ˈskændiəm) is a chemical element that has the symbol Sc and atomic number 21. A silvery white metal that is always present as compounds, scandium ores occur as rare minerals from Scandinavia and elsewhere, and it is sometimes considered… …   Wikipedia

  • Scandium — Calcium ← Scandium → Titane …   Wikipédia en Français

  • SCANDIUM — De Scandia , Scandinavie. Symbole chimique: Sc Numéro atomique: 21 Masse atomique: 44,95 Point de fusion: 1 539 0C Point d’ébullition: 2 832 0C Densité (à 25 0C): 2,989 Élément chimique du groupe des terres rares, mou et d’aspect argenté, prédit… …   Encyclopédie Universelle

  • Scandium — Scan di*um, n. [NL. So called because found in Scandinavian minerals.] (Chem.) A rare metallic element of the boron group, whose existence was predicted under the provisional name {ekaboron} by means of the periodic law, and subsequently… …   The Collaborative International Dictionary of English

  • Scandĭum — Sc, chemisch einfacher Körper, findet sich im Euxenit, Gadolinit, Yttrotitanit und Keilhauit, besitzt das Atomgewicht 44,1, bildet ein weißes, unschmelzbares Oxyd (Skandinerde) Sc2O3 vom spez. Gew. 3,8, das sich in kochender Salzsäure und… …   Meyers Großes Konversations-Lexikon

  • Scandium — Sc, Atomgew. 44,1, findet sich im Euxenit und einigen andern seltenen Mineralien. Es in nur in einer Reihe von Verbindungen bekannt und ist mit dem von Mendelejeff auf Grund des periodischen Systems der Elemente vorausgesetzten Ekabor identisch.… …   Lexikon der gesamten Technik

  • scandium — Symbol: Sc Atomic number: 21 Atomic weight: 44.956 Rare soft silvery metallic element belonging to group 3 of the periodic table. There are ten isotopes, nine of which are radioactive and have short half lives. Predicted in 1869 by Mendeleev,… …   Elements of periodic system

  • scandium — [skan′dē əm] n. [ModL: so named (1879) by L. F. Nilson (1840 99), Swed chemist < ML Scandia, Scandinavia (source of the ore from which it was isolated) + IUM] a rare, silvery white, metallic chemical element occurring with various rare earth… …   English World dictionary

  • Scandium — Eigenschaften …   Deutsch Wikipedia

  • Scandium — Scạn|di|um 〈n.; s; unz.; chem. 〉 hellgraues, glänzendes Metall der seltenen Erden, Ordnungszahl 21 [neulat., nach Scandia, dem lat. Namen für Südskandinavien] * * * Scạn|di|um [nlat. Scandia = Skandinavien; ↑ ium (1)], das; s: Symbol: Sc:… …   Universal-Lexikon

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