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niobium
Columbia Encyclopedia entry: niobium
Niobiumnīō'bēəm, metallic chemical element; symbol Nb; at. no. 41; at. wt. 92.9064; m.p. about 2,468°C; b.p. 4,742°C; sp. gr. 8.57 at 20°C; valence +2, +3, +4, or +5. Niobium is a rare, soft, malleable, ductile, gray-white metal with a body-centered cubic crystalline structure. In its physical and chemical properties it resembles tantalum, the element below it in Group 5 of the periodic table. At normal temperatures it is insoluble in solutions of most acids or alkalies. It reacts readily at high temperatures with oxygen, carbon, the halogens, nitrogen, and sulfur; it must be placed in a protective atmosphere when processed. It forms four oxides; the pentoxide, Nb2O5, is the basis of a series of salts called niobates. Niobium is important in the production of high-temperature-resistant alloys and special stainless steels; large amounts of niobium have been used in the U.S. space program. Niobium carbide is used in cutting tools. The name niobium was officially adopted by the International Union of Pure and Applied Chemistry (IUPAC) in 1949; the name columbium (symbol Cb) was used for the element in some countries prior to that and continued to be used by many metallurgists and commercial producers of the metal. Niobium is widely distributed in nature; it is about one and a half times as abundant as lead. It occurs in the minerals columbite and tantalite, together with tantalum. Separating niobium and tantalum is difficult. The element was discovered in 1801 by Charles Hatchett and first isolated in 1864 by C. W. Blomstrand.

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Wikipedia search results for: Niobium
From Wikipedia, the free encyclopedia
Niobium , or columbium, is the chemical element with the symbol Nb and the atomic number 41. A rare, soft, grey, ductile transition metal, niobium is found in the minerals pyrochlore, the main commercial source for niobium, and columbite. Niobium has physical and chemical properties similar to those of the element tantalum, and the two are therefore difficult to distinguish. The English chemist Charles Hatchett reported a new element similar to tantalum in 1801, and named it columbium. In 1809, the English chemist William Hyde Wollaston wrongly concluded that tantalum and columbium were identical. The German chemist Heinrich Rose determined in...more »
Columbia Encyclopedia search results: niobium
Results 1 - 10  of 10
  • Periodic Table of the Elements: Niobium

    Periodic Table of the Elements: NiobiumAtomic Number:41Atomic Symbol:NbNiobiumAtomic Weight:92.9064ElectronConfiguration:2 · 8 · 1812 · 1

  • Nb

    Nb, symbol for the element niobium.

  • columbium

    Columbium, symbol Cb, former name of the chemical element niobium.

  • Cb

    Cb, formerly the symbol for the element columbium, now called niobium (Nb).

  • vanadium

    , metallic chemical element; symbol V; at. no. 23; at. wt. 50.9415; m.p. about 1,890°C; b.p. 3,380°C; sp. gr. about 6 at 20°C; valence +2, +3, +4, or +5. Vanadium is a soft, ductile, silver-gr...

  • Rose, Gustav

    Rose, Gustav, 1798–1873, German mineralogist. He served as professor at the Univ. of Berlin from 1839. Noted especially as a crystallographer, he advanced the scientific study of rocks. His br...

  • tantalum

    Tantalum [from Tantalus], metallic chemical element; symbol Ta; at. no. 73; at. wt. 180.9479; m.p. 2,996°C; b.p. 5,400±100°C; sp. gr. 16.65 at 20°C; valence +2, +3, +4, or +5. Tantalum is a ra...

  • dubnium

    Dubnium, artificially produced radioactive chemical element; symbol Db; at. no. 105; mass number of most stable isotope 262; m.p., b.p., and sp. gr. unknown; valence +5. Situated in Group 5 of...

  • Greenland

    Greenland, Green. Kalaallit Nunaat, Dan. Grønland, the largest island in the world (2005 est. pop. 56,000), 836,109 sq mi (2,166,086 sq km), self-governing overseas administrative division of ...

  • Elements (table)

    ElementsElementSymbolAtomic NumberAtomic Weight1Melting Point(Degrees Celsius)Boiling Point(Degrees Celsius)1 Parentheses indicate most stable isotope.actiniumAc89227.02781050.3200....

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