Nickels (11951)
Nickel (IPA: /ˈnɪkəl/) is a metallic chemical element in the periodic table that has the symbol Ni and atomic number 28. more...
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Characteristics
Nickel is a silvery white metal that takes on a high polish. It belongs to the transition metals, and is hard and ductile. It occurs combined with sulfur in millerite, with arsenic in the mineral niccolite, and with arsenic and sulfur in nickel glance.
Because of its permanence in air and its inertness to oxidation, it is used in some coins for plating iron, brass, etc., for chemical apparatus, and in certain alloys, as German silver. It is magnetic, and is very frequently accompanied by cobalt, both being found in meteoric iron. It is chiefly valuable for the alloys it forms, especially many superalloys.
Nickel is one of the five ferromagnetic elements. However, the U.S. "nickel" coin is not magnetic, because it actually is mostly (75%) copper. The Canadian nickel minted at various periods between 1922-81 was 99.9% nickel, and these were magnetic.
The most common oxidation state of nickel is +2, though 0, +1, +3 and +4 Ni complexes are observed. It is also thought that a +6 oxidation state may exist, however, results are inconclusive.
The unit cell of nickel is an FCC with a lattice parameter of 0.356 nm giving a radius of the atom of 0.126 nm.
Nickel-62 is the most stable nuclide of all the existing elements; it is more stable even than Iron-56.
History
The use of Nickel is ancient, and can be traced back as far as 3500 BC. Bronzes from what is now Syria had a nickel content of up to two percent. Further, there are Chinese manuscripts suggesting that "white copper" (e.g. baitung) was used in the Orient between 1400 and 1700 BC. However, because the ores of nickel were easily mistaken for ores of silver, any understanding of this metal and its use dates to more contemporary times.
Minerals containing nickel (e.g. kupfernickel, meaning copper of the devil ("Nick"), or false copper) were of value for colouring glass green. In 1751, Baron Axel Fredrik Cronstedt was attempting to extract copper from kupfernickel (now called niccolite), and obtained instead a white metal that he called nickel.
Coins of pure nickel were first used in 1881 in Switzerland.
Biological role
Although not recognized until the 1970's, nickel plays numerous roles in biology. In fact, the first protein ever crystallized, urease contains nickel, which assists in the hydrolysis of urea. The NiFe-hydrogenases contain nickel in addition to iron-sulfur clusters. Such -hydrogenases characteristically oxidise H2. A nickel-tetrapyrrole coenzyme, F430, is present in the methyl coenzyme M reductase which powers methanogenic archaea.
Read more at Wikipedia.org
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