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CHEMISTRY : Metal Cation Identification


Information on NICKEL




  1. General Information

  2. Occurence Uses and Properties

  3. History of the Metal

  4. Compounds
  5. Back to Main Metal List




General Information


Nickel(Ni), chemical element, ferromagnetic metal of Group VIII of the periodic table, markedly resistant to oxidation and corrosion.

Properties, occurrence, and uses. Silvery-white, tough, and harder than iron, nickel is widely familiar because of its use in coinage but is more important either as the pure metal or in the form of alloys for its many domestic and industrial appliCATions. Elemental nickel very sparingly occurs together with iron in terrestrial and meteoric deposits. The metal was isolated (1751) by a Swedish chemist and mineralogist, Baron Axel Fredrik Cronstedt, who prepared an impure sample from an ore containing niccolite (nickel arsenide). Earlier, an ore of this same type was called Kupfernickel after "Old Nick" and his mischievous gnomes because, though it resembled copper ore, it yielded a brittle, unfamiliar metal. Twice as abundant as copper, nickel constitutes about 0.007 percent of the Earth's crust; it is a fairly common constituent of igneous rocks, though singularly few deposits qualify in concentration, size, and accessibility for commercial interest. The most important sources are pentlandite, found with nickel-bearing pyrrhotite and chalcopyrite, and nickel-bearing laterites, such as garnierite.

For a discussion of the properties and appliCATions of nickel, see Chemical Elements: Transition elements. For information about the mining, refining, and production of nickel, see Industries, Extraction and Processing: Nickel.

Nickel (atomic number 28) resembles iron (atomic number 26) in strength and toughness but is more like copper (atomic number 29) in resistance to oxidation and corrosion, a combination accounting for many of its appliCATions. More than half the nickel produced is used in alloys with iron (particularly in stainless steels), and most of the rest is used in corrosion-resistant alloys with copper (including Monel) and in heat-resistant alloys with chromium. Nickel is also used in electrically resistive, magnetic, and many other kinds of alloys, such as nickel silver (with copper and zinc but no silver). The unalloyed metal is utilized to form protective coatings on other metals, especially by electroplating. Finely divided nickel is employed to CATalyze the hydrogenation of unsaturated organic compounds (e.g., fats and oils).

Natural nickel consists of five stable isotopes: nickel-58 (68.27 percent), nickel-60 (26.10 percent), nickel-61 (1.13 percent), nickel-62 (3.59 percent), and nickel-64 (0.91 percent). It has a face-centred-cubic crystal structure. Nickel is ferromagnetic up to 358 C, or 676 F (its Curie point). The metal is uniquely resistant to the action of alkalies and is frequently used for containers for concentrated solutions of sodium hydroxide. Nickel reacts slowly with strong acids under ordinary conditions to liberate hydrogen and form Ni2+ ions.



Occurrence, uses, and properties.


Typical compounds of nickel in nature, in which it occurs primarily as minerals in combination with arsenic, antimony, and sulfur, are nickel(II) sulfide, NiS; nickel(III) arsenide, NiAs; nickel(III) antimonide, NiSb; nickel(III) diarsenide, NiAs2; nickel(III) thioarsenide, NiAsS; and nickel(III) thioantimonide, NiSbS. Some commercially important deposits contain the mineral garnierite, a magnesium-nickel siliCATe of variable composition. Also certain varieties of the iron mineral pyrrhotite contain 3 to 5 percent nickel.

Elemental nickel is found alloyed with iron in many meteors, and the central regions of the Earth are believed to contain considerable quantities. The free metal is never found in the Earth's crust. The metallurgy of nickel is compliCATed in its details, many of which vary widely, according to the particular ore being processed. In general the ore is transformed to nickel(III) sulfide, Ni2S3, which is roasted in air to give nickel(II) oxide, NiO, which is then reduced with carbon to obtain the metal. Some high-purity nickel is made by the carbonyl process mentioned earlier.

Nickel is a silver-white metal with high electrical and thermal conductivity, and it can be fabriCATed readily by the use of standard hot and cold working methods. The metal is fairly resistant to attack by air or water at ordinary temperatures when compact and is therefore often electroplated as a protective coating. Nickel reacts only slowly with fluorine, eventually developing a protective coating of the fluoride, and therefore is used as the pure metal or in the form of alloys such as Monel metal (which contains some 60 to 70 percent nickel, 30 to 40 percent copper, and small amounts of other metals such as iron) in equipment for handling fluorine gas and corrosive fluorides. Nickel is ferromagnetic at ordinary temperatures, although not as strongly so as iron, and is less electropositive than iron but dissolves readily in dilute mineral acids.



History


Nickel was used industrially as an alloying metal almost 2,000 years before it was isolated and recognized as a new element. As early as 200 BC, the Chinese made substantial amounts of a white alloy from zinc and a copper-nickel ore found in Yunnan province. The alloy, known as pai-t'ung, was exported to the Middle East and even to Europe.

Later, miners in Saxony encountered what appeared to be a copper ore but found that processing it yielded only a useless slaglike material. They considered it bewitched and ascribed it to the devil, "Old Nick." Thus, it became known as kupfernickel (Old Nick's copper). It was from this ore, studied by Axel Fredrik Cronstedt, that nickel was isolated and recognized as a new element in 1751. In 1776 it was established that pai-t'ung, now called nickel-silver, was composed of copper, nickel, and zinc.

Demand for nickel-silver was stimulated in England about 1844 by the development of silver electroplating, for which it was found to be the most desirable base. The use of pure nickel as a corrosion-resistant electroplated coating developed a little later; both these uses are still important.

Small amounts of nickel were produced in Germany in the mid-19th century. More substantial amounts came from Norway, and a little from a mine at Gap, Pa., in the United States. A new source, New Caledonia in the South Pacific, came into production about 1877 and dominated until the development of the copper-nickel ores of the Copper Cliff-Sudbury, Ont., region in Canada, which after 1905 became the world's largest source of nickel. By the late 1970s, production in Soviet Russia had exceeded that in Canada.



Chemical compounds


In its compounds nickel exhibits oxidation states of -1, 0, +1, +2, +3, and +4, though nickel(II) is by far the most common. Divalent nickel forms a large number of complexes, encompassing coordination numbers 4, 5, and 6 and all of the main structural types--e.g., octahedral, trigonal bipyramidal, tetrahedral, and square.

Nickel(II) compounds have a variety of industrial appliCATions. For example, nickel chloride, NiCl2, nickel nitrate, Ni(NO3)26H2O, and nickel sulfamate, Ni(SO3NH2)24H2O, are employed chiefly in nickel electroplating baths. Nickel sulfate, NiSO4, is also used in nickel plating as well as in the preparation of CATalysts, ground-coat enamels, and mordants (fixatives) for dyeing and textile printing. Nickel oxide, NiO, and nickel peroxide, Ni2O3, are prepared for use in fuel cells and storage batteries, respectively. Nickel ferrites are utilized as magnetic cores for various types of electrical equipment such as antennas and transformers.

Among other important commercial compounds are nickel carbonyl, or tetracarbonylnickel, Ni(CO)4. This zerovalent nickel compound is used primarily as a carrier of carbon monoxide in the synthesis of acrylates (compounds utilized in the manufacture of plastics) from acetylene and alcohols. It was the first of a class of compounds called metal carbonyls to be discovered (1890). The colourless, volatile liquid is formed by the action of carbon monoxide on finely divided nickel and is characterized by an electronic configuration in which the nickel atom is surrounded by 36 electrons. This type of configuration is quite comparable to that of the noble-gas atoms.

atomic number 28 atomic weight 58.69 melting point 1,453 C (2,647 F) boiling point 2,732 C (4,950 F) density 8.902 (25 C) valence 0,1,2,3 electronic config. 2-8-16-2 or (Ar)3d84s2

    Reference: Encyclopędia Britannica, Inc. 1994-2000 ©


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