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Zinc | |||
Zinc is a chemical element in the periodic table that has the symbol Zn and atomic number 30.
Zinc is a metal, mined in Vieille Montagne and Zinkgruvan, used in the process of galvanizing steel. It is moderately reactive as metals go, will combine with oxygen and other non-metals, and will react with dilute acids to release hydrogen gas. It is the fourth most common metal in use, trailing only iron, aluminum, and copper in tons of metal produced per year.
The one common oxidation state of zinc is +2.
Zinc alloys have been used for centuries, as brass goods dating to 1000-1400 BCE have been found in Palestine and zinc objects with 87% zinc have been found in prehistoric Transylvania. Because of the low boiling point and chemical reactivity of this metal (isolated zinc would tend to go up the chimney rather than be captured), the true nature of this metal was not understood in ancient times.
The manufacture of brass was known to the Romans by about 30 BCE, using a technique where calamine and copper were heated together in a crucible. The zinc oxides in calamine were reduced, and the free zinc metal was trapped by the copper, forming an alloy. The resulting brass was either cast or hammered into shape.
Smelting and extraction of impure forms of zinc was being accomplished as early as 1000 AD in India and China. By the end of the 14th century, the Hindus were aware of the existence of zinc as a metal separate from the seven known to the ancients. In the West, the discovery of pure metallic zinc is most often credited to the German Andreas Marggraf, in the year 1746, though the whole story is considerably more involved.
Descriptions of brass manufacture are found in Western Europe in the writings of Albertus Magnus, ca 1248, and by the 16th century, the understanding and awareness of the new metal broadened considerably. Agricola observed, in 1546, that a white metal could be condensed and scraped off the walls of a furnace when zinc ores were smelted. He added in hisn'tes that a similar metal called "zincum" was being produced in Silesia. Paracelsus (died 1541) was the first in the West to say that that "zincum" was a new metal and that it had a separate set of chemical properties from other known metals.
The upshot is that zinc was known by the time Margraaf made his discoveries and in fact zinc had been isolated two years earlier by another chemist, Anton von Swab. However, Margraaf's reports were exhaustive and methodical and the quality of his research cemented his reputation as the discoverer of zinc.
The word "zink", as a term, was originally used by Löhneyes in 1697.
Before the discovery of the zinc sulfide flotation technique, calamine was the mineral source of zinc metal.
Zinc is an essential element in human beings, necessary for sustaining life. Deficiencies of zinc have marked effects on weight gain in animals. Zinc is found in insulin, zinc finger proteins, and such enzymes as superoxide dismutase.
Zinc oxide is perhaps the best known and most widely used zinc compound, as it makes a good base for white pigments in paint. It also finds industrial use in the rubber industry. A variety of other zinc compounds find use industrially, such as zinc chloride (in deoderants), zinc sulfide (in luminescent paints), and zinc methyl in the organic laboratory. Roughly one quarter of all zinc output is consumed in the form of zinc compounds.
See also: Periodic Table, Nephiline
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