indium

indium
/in"dee euhm/, n. Chem.
a rare metallic element, soft, white, malleable, and easily fusible, found combined in various ore minerals, esp. sphalerite: so called from the two indigo-blue lines in its spectrum. Symbol: In; at. wt.: 114.82; at. no.: 49; sp. gr.: 7.3 at 20°C.
[1860-65; < NL, equiv. to ind(icum) INDIGO + -ium -IUM]

* * *

 chemical element, rare metal of main Group 13 (IIIa, or boron group) of the periodic table. Of a brilliant, silvery-white lustre, indium was discovered (1863) by Ferdinand Reich and Theodor Richter while they were examining zinc ore samples. The presence of a predominant indigo spectral line suggested the name. Softer than lead and quite plastic, indium can be scratched with a fingernail and can undergo almost limitless deformation. Like tin, the pure metal emits a high-pitched “cry” when bent. Indium is about as rare as silver. The Earth's crust contains on the average about 0.05 part per million indium by weight. The element does not occur uncombined nor in independent minerals but as a trace in many minerals, particularly those of zinc and lead, from which it is obtained as a by-product.

      Indium has the unusual property when molten of clinging to (wetting) clean glass and other surfaces; this makes it valuable for producing hermetic seals between glass, metals, quartz, ceramics, and marble. Indium is used in coating aircraft engine bearings because it improves corrosion resistance and enables the surface to retain a more adherent oil film. Indium is an ingredient in some low-melting alloys used in sprinkler heads, fire-door links, and fusible plugs. The metal is extensively employed in the manufacture of semiconductor devices and for soldering various parts of germanium transistors and rectifiers. Indium also is used to measure the thermal neutron flux of nuclear reactors and to monitor neutrons for the protection of personnel and equipment. Natural indium is a mixture of two isotopes: indium-113 (4.28 percent) and indium-115 (95.72 percent).

      Indium metal is unaffected by air at ordinary temperatures, but at a red heat it burns with a blue-violet flame to form the yellow oxide In2O3. This oxide is easily reduced to the metal, and on strong heating it loses oxygen to give the monoxide, In2O, where indium is in the +1 oxidation state. Indium hydroxide dissolves in both acids and alkalies.

      Indium is an amphoteric element; it dissolves in acids to give indium salts and it also dissolves in concentrated alkalies to give indates. However, it is unaffected by potassium hydroxide or boiling water. When heated in the presence of the halogens or sulfur, direct combination takes place. Though a few authentic indium compounds (e.g., halides) have been prepared in which the element is in the +1 oxidation state, indium commonly displays the +3 state in its compounds. With the main Group 15 (Va) elements, indium forms compounds (indium phosphide, arsenide, antimonide) that have semiconductor properties.

      All anhydrous triply charged indium derivatives, except indium trifluoride, formula InF3, are covalent. There is a marked tendency for two of the outer electrons of the indium atom (the outer 5s2 electrons) not to be used in bonding; this circumstance results in singly charged indium compounds.

atomic number
49
atomic weight
114.82
melting point
156.61° C
boiling point
2,080° C
specific gravity
7.31 (20° C)
oxidation states
+1, +3
electronic config.
[Kr]4d105s25p1

* * *


Universalium. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Indium — Cadmium ← Indium → Étain Ga …   Wikipédia en Français

  • INDIUM — De indicum , indigo Symbole chimique: In Numéro atomique: 49 g Masse atomique: 114,82 Point de fusion: 156,6 0C Point d’ébullition: 2 080 0C Densité (à 20 0C): 7,31. Élément chimique du groupe des métaux rares, blanc argenté brillant, mou,… …   Encyclopédie Universelle

  • indium — ÍNDIUM s.n. v. indiu. Trimis de valeriu, 13.09.2007. Sursa: DEX 98  ÍNDIUM s.n. v. indiu. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • Indium — In di*um, n. [NL. See {Indigo}.] (Chem.) A rare metallic element, of atomic number 49, discovered in certain ores of zinc, by means of its characteristic spectrum of two indigo blue lines; hence, its name. In appearance it resembles zinc, being… …   The Collaborative International Dictionary of English

  • Indĭum — In, Metall, findet sich in geringer Menge in manchen Zinkblenden (Freiberg, Breitenbrunn, Schönfeld) und in dem aus diesen gewonnenen Zink (Freiberger Zink bis 0,1 Proz.), im zinkischen Ofenbruch der Juliushütte bei Goslar, in Hüttenprodukten aus …   Meyers Großes Konversations-Lexikon

  • Indium — In (Atomgewicht 113,5, spez. Gew. 7,4), ein silberweißes, an der Luft unveränderliches weiches Metall, das bei 176° schmilzt und in Weißglut flüchtig ist und bei hoher Temperatur mit blauer Flamme zu Oxyd In2O2 verbrennt; gehört zu den seltenen… …   Lexikon der gesamten Technik

  • Indium — (chem. Zeichen In), sehr seltenes, weißes, weiches Metall, findet sich nur in zinkischen Erzen und deren Produkten; spez. Gewicht 7,4, Atomgewicht 113,1, Schmelzpunkt 176°, oxydiert sich an der Luft nicht …   Kleines Konversations-Lexikon

  • indium — Symbol: In Atomic number: 49 Atomic weight: 114.82 Soft silvery element belonging to group 13 of the periodic table. The most common natural isotope is In 115, which has a half life of 6*10^4 years. Five other radioisotopes exist. Discovered in… …   Elements of periodic system

  • índium — s. m. O mesmo que índio (metal) …   Dicionário da Língua Portuguesa

  • indium — ► NOUN ▪ a soft, silvery white metallic chemical element resembling zinc, used in some alloys and semiconductor devices. ORIGIN from INDIGO(Cf. ↑indigo) (because there are two characteristic indigo lines in its spectrum) …   English terms dictionary

  • indium — [in′dē əm] n. [ModL: so named (1863) by F. Reich (1799 1882) & H. T. Richter (1824 98), Ger metallurgists < L indicum, INDIGO + IUM, because of the two indigo lines in its spectrum] a rare metallic chemical element, soft, ductile, and silver… …   English World dictionary

Share the article and excerpts

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