Tin
Tin is a metal element which has an atomic weight of tin 118.69 and an atomic number of 50. Its atomic symbol is Sn, from the Latin term stannum. Tin is a silver-white metal with a bluish tint. It has a melting point of 449.42°F (231.9°C) and a boiling point of 4715.6°F (2602°C). Because of its highly crystalline structure, tin, as it is bent, makes a moaning sound called "tin cry."
Upon cooling, tin undergoes unusual changes in its crystalline structure, transforming from white (beta) tin, with a tetragonal structure, to gray (alpha) tin, which has a cubic structure, at about 64°F (18°C). This transformation is called the "tin pest" by metallurgists because alpha tin is useless for their purposes. However, adding small quantities of antimony or bismuth to tin will prevent this from occurring.
Tin was known in ancient times. Its earliest use was as an alloy with copper in bronze. A small amount of tin added to copper makes the metal harder and more malleable, more practical than pure copper for making tools and weapons. It is thought that the use of tin as an alloy was inadvertent, that the tin was not realized to be a separate metal.
The production of tin begins with mining of low-grade deposits, mainly in cassiterite (SnO2). Although Bolivia is the primary producer of tin, other deposits are found in Malaysia, Indonesia, Thailand, Zaire, and Nigeria. There are no significant deposits in the United States. Tin is then purified by reduction in a reverberatory furnace with coal.
Tin has a variety of uses. It is alloyed with copper and antimony to make pewter, which is very easily worked. Pewter was popular for use in pots and dinnerware from the thirteenth century through the early nineteenth century.
Tin is currently employed as a soft solder. It is often used as a coating for other metals to retard corrosion, and it is used to plate steel cans ("tin cans") for preserving food. Until recently, tin-plated iron or steel was used as a roofing material, especially in the Midwestern United States. "Tin roofs" had a reputation for durability. However, this material has largely been replaced by zinc -plated metal roofs which are more common.
Tin salts are used for electrically conductive coatings, specifically for panel lighting and frost-free windshields. A new alloy of tin and niobium, a rare metal used in jewelry and industry, has proven to be useful in the creation of superconductive magnets, which use a fraction of the power needed in standard electromagnets.
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