Tin is a
chemical elementwith the symbol Sn ( _la. stannum) and atomic number50. This silvery, malleable poor metalthat is not easily oxidized in air and resists corrosion, is found in many alloys and is used to coat other metals to prevent corrosion. Tin is obtained chiefly from the mineral cassiterite, where it occurs as an oxide. It can be alloyed with copperto make bronze. Pewteralloys contain from 85% up to 99% tin.
Tin is a malleable,
ductile, highly crystalline, silvery-white metal; when a bar of tin is bent, a strange crackling sound, known as the tin cry, can be heard due to the twinning of the crystals. Tin is malleable at ordinary temperatures but is brittle when it is cooled.
Tin resists corrosion from
distilled, sea and soft tap water, but can be attacked by strong acids, alkalis, and by acid salts. Tin acts as a catalystwhen oxygenis in solution and helps accelerate chemical attack. Tin forms the dioxide SnO2 when it is heated in the presence of air. SnO2, in turn, is feebly acidic and forms stannate(SnO32-) salts with basic oxides. Tin can be highly polished and is used as a protective coat for other metals in order to prevent corrosion or other chemical action. This metal combines directly with chlorineand oxygen and displaces hydrogenfrom dilute acids.
Tin's chemical properties fall between those of metals and non-metals, just as the
semiconductors siliconand germaniumdo. Tin has two allotropes at normal pressure and temperature: gray tin and white tin. A third allotrope, called brittle tin, exists at temperatures above 161 °C. Below 13.2 °C, it exists as "gray" or alpha tin, which has a cubic crystal structuresimilar to siliconand germanium. Gray tin has no metallic properties at all, is a dull-gray powdery material, and has few uses, other than a few specialized semiconductorapplications. Although the transformation temperature is 13.2 °C, the change does not take place unless the metal is of high purity, and only when the exposure temperature is well below 0 °C. [Mel Schwartz." Encyclopedia of Materials, Parts and Finishes, 2nd edition", section "Tin and Alloys, Properties". CRC Press, 2002. ISBN 1-56676-661-3] This process is known as "tin disease" or " tin pest". Tin pest was a particular problem in northern Europein the 18th century as organ pipesmade of tin alloy would sometimes be affected during long cold winters. Some sources also say that during Napoleon's Russian campaign of 1812, the temperatures became so cold that the tin buttons on the soldiers' uniforms disintegrated, contributing to the defeat of the Grande Armée. The veracity of this story is debatable, because the transformation to gray tin often takes a reasonably long time. [Le Coureur, Penny, and Jay Burreson. "Napoleon's Buttons: 17 Molecules that Changed History". New York: Penguin Group USA, 2004.] Commercial grades of tin (99.8%) resist transformation because of the inhibiting effect of the small amounts of bismuth, antimony, lead, and silver present as impurities. Alloying elements such as copper, antimony, bismuth, cadmium, and silver increase its hardness. Tin tends rather easily to form hard, brittle intermetallic phases, which are often undesirable. It does not form wide solid solution ranges in other metals in general, and there are few elements that have appreciable solid solubility in tin. Simple eutectic systems,however, occur with bismuth, gallium, lead, thallium, and zinc. [Mel Schwartz."Encyclopedia of Materials, Parts and Finishes, 2nd edition", section "Tin and Alloys, Properties". CRC Press, 2002. ISBN 1-56676-661-3]
Old English: "tin", Old Latin: "plumbum candidum" ("white lead"), Old German: "tsin", Late Latin: "stannum") is one of the earliest metals known and was used as a component of bronzefrom antiquity. Because of its hardening effect on copper, tin was used in bronze implements as early as 3,500 BC. A shipwreck at Uluburun, Turkey dating to 1336 BC contains a shipment of tin, perhaps originating in Afghanistan. [Martin Ewans. "Afghanistan". Harper Collins, 2001. ISBN 0-06-050508-7] European tin mining is believed to have started in Cornwalland Devon(esp. Dartmoor) in Classical times, and a thriving tin trade developed with the civilizations of the Mediterranean. [cite web |url=http://romans.etrusia.co.uk/whyinvade.php |title=Why Claudius invaded Britain |accessdate=2007-01-12 |last=Wake |first=H. |date=2006-04-07 |format=HTML |work=Etrusia - Roman History ] [cite web |url=http://romanhistory.20m.com/project1c.htm |title=The Romano-British Amphora Trade to 43 A.D: An Overview |accessdate=2007-01-12 |last=McKeown |first=James |date=1999-01 |format=HTML ] However the lone metal was not used until about 600 BC. The last Cornish tin mine, at South Croftynear Camborne, closed in 1998 bringing 4,000 years of mining in Cornwall to an end, but as of 2007 increased demand from China may lead to its re-opening. [cite web |url=http://commentisfree.guardian.co.uk/leo_hickman/2007/11/the_return_of_tin.html |title=The Return of Tin |accessdate=2007-12-04 |last=Hickman |first=Leo |date=2007-11-30 |format=HTML ]
The word "tin" has cognates in many Germanic and
Celtic languages. The " American Heritage Dictionary" speculates that the word was borrowed from a pre- Indo-European language. The later name "stannum" and its Romance derivatives come from the lead-silver alloy of the same name for the finding of the latter in ores; the former "stagnum" was the word for a stale pool or puddle.
In modern times, the word "tin" is often improperly used as a generic phrase for any silvery metal that comes in sheets. Most everyday materials that are commonly called "tin", such as
aluminium foil, beverage cans, corrugated building sheathing and tin cans, are actually made of steelor aluminium, although tin cans (tinned cans) do contain a thin coating of tin to inhibit rust. Likewise, so-called "tin toys" are usually made of steel, and may or may not have a coating of tin to inhibit rust. The original Ford Model Twas known colloquially as the Tin Lizzy.
Historical Cornwall was the major tin producer, this changed after large amounts of tin have been found in the
Bolivian tin belt and the east asian tin belt stretching from China through Thailandand Laosto Malayaand Indonesia. The tin produceres founded in 1931 the International Tin Comitteefollowed in 1956 by the International Tin Councila institution to control the tin market. After the collapse of the market in October 1985 the price for tin nearly halved.
In 2007, the
People's Republic of Chinawas the largest producer of tin, where the tin deposites are concentrated in the southeast Yunnan tin belt, [cite journal | title = Classification and type association of tin deposits in Southeast Yunnan Tin Belt | journal = Chinese Journal of Geochemistry | volume = 10 | issue = 1 | year = 1991 | doi = 10.1007/BF02843295 | pages = 21–35] with 43% of the world's share, followed by Indonesiaand Peru, reports the USGS. [ [http://minerals.usgs.gov/minerals/pubs/commodity/tin/mcs-2008-tin.pdf US Geological Survey - Mineral Commodity Summary - Tin 2008] ]
Tin is produced by reducing the
orewith coalin a reverberatory furnace. This metal is a relatively scarce element with an abundance in the Earth's crust of about 2 ppm, compared with 94 ppm for zinc, 63 ppm for copper, and 12 ppm for lead. Most of the world's tin is produced from placer deposits. The only mineralof commercial importance as a source of tin is cassiterite(SnO2), although small quantities of tin are recovered from complex sulfides such as stannite, cylindrite, franckeite, canfieldite, and teallite. Secondary, or scrap, tin is also an important source of the metal. Tasmaniahosts some deposits of historical importance, most notably Mount Bischoffand Renison Bell. New deposits are also reported to be in southern Mongolia.
It is estimated that, at current consumption rates, the Earth will run out of tin in 40 years. [cite journal | date=
May 26, 2007| journal = New Scientist | volume = 194 | issue = 2605 | pages = 38–39 | issn = 0262 4079 | title = How Long Will it Last? ] However Lester Brown has suggested tin could run out within 20 years based on an extremely conservative extrapolation of 2% growth per year.Brown, Lester "Plan B 2.0", New York: W.W. Norton, 2006. p. 109] However this is offset by the increased use of secondary, or scrap tin, as a readily available source of the metal.
"See also "
Metall and Alloy
Tin bonds readily to
iron, and is used for coating leador zinc and steelto prevent corrosion. Tin-plated steelcontainers are widely used for food preservation, and this forms a large part of the market for metallic tin. Speakers of British English call them "tins"; Americans call them "cans" or "tin cans". One thus-derived use of the slang term " tinnie" or "tinny" means "can of beer". The tin whistleis so called because it was first mass-produced in tin-plated steel.
*Tin foil was once a common wrapping material for foods and drugs; replaced in the early 20th century by the use of
aluminium foil, which is now commonly referred to as "tin foil". Hence one use of the slang term " tinnie" or "tinny" for a small retail package of a drug such as cannabis or for a can of beer.
*Tin is used extensively for alloys, some important tin
alloysare bronze, bell metal, Babbitt metal, die castingalloy, pewter, phosphor bronze, soft solder, and White metal.
*Most metal pipes in a
pipe organare made of varying amounts of a tin/lead alloy, with 50%/50% being the most common. The amount of tin in the pipe defines the pipe's tone, since tin is the most tonally resonant of all metals. When a tin/lead alloy cools, the lead cools slightly faster and makes a mottled or spotted effect. This metal alloy is referred to as spotted metal.
*Window glass is most often made via floating molten
glasson top of molten tin (creating float glass) in order to make a flat surface (this is called the " Pilkington process").
*Tin is also used in
solders for joining pipes or electric circuits, in bearing alloys, in glass-making, and in a wide range of tin chemical applications. Although of higher melting point than a lead-tin alloy, the use of pure tin or tin alloyed with other metals in these applications is rapidly supplanting the use of the previously common lead–containing alloys in order to eliminate the problems of toxicity caused by lead.
*Tin becomes a
superconductorbelow 3.72 K. In fact, tin was one of the first superconductors to be studied; the Meissner effect, one of the characteristic features of superconductors, was first discovered in superconducting tin crystals. The niobium-tin compound Nb3Sn is commercially used as wires for superconducting magnets, due to the material's high critical temperature (18 K) and critical magnetic field (25 T). A superconducting magnet weighing only a couple of kilograms is capable of producing magnetic fields comparable to a conventional electromagnetweighing tons.
*For a long time the
antifoulingproperty of organotincompounds was used for the preservation of wood and to prevent growth of marine organisms on ships. Tributyltinwas used as additive for ship paint. The use declined after organotin compounds where recognised as persistent organic pollutantswith a extremly high toxicity for some marine organism, for example dog whelk. [cite web | title = TIN HAZARDS TO FISH, WILDLIFE, AND INVERTEBRATES: A SYNOPTIC REVIEW | first = Ronald | last = Eisler | publisher = U.S. Fish and Wildlife Service Patuxent Wildlife Research Center | url = http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA322822&Location=U2&doc=GetTRDoc.pdf ] The EU banned the use of organotin compounds in 2003. [ [http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2003:115:0001:0011:EN:PDF REGULATION (EC) No 782/2003 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 14 April 2003 on the prohibition of organotin compounds on ships] ]
*The most important salt formed is stannous chloride, which has found use as a reducing agent and as a
mordantin the calico printing process. Electrically conductive coatings are produced when tin salts are sprayed onto glass. These coatings have been used in panel lighting and in the production of frost-free windshields.
*Tin is added to some dental care products [ [http://www.crest.com/prohealth/home.jsp Crest Pro Health] , [http://www.colgate.com/app/Colgate/US/OC/Products/FromTheDentist/GelKamStannousFluorideGel.cvsp Colgate Gel-Kam] ] as
stannous fluoride(SnF2). Stannous fluoridecan be mixed with calcium abrasives while the more common sodium fluoridegradually becomes biologically inactive combined with calcium. [cite journal | date = April 1989| journal = Journal of Dentistry | volume = 17 | issue = 2 | pages = 47–54 | pmid = 2732364 | title = The State of Fluorides in Toothpastes. | doi = 10.1016/0300-5712(89)90129-2 | last = Hattab | first = F. ] It has also been shown to be more effective than sodium fluoridein controlling gingivitis. [cite journal | date= 1995| journal = The Journal of Clinical Dentistry | volume = 6 | issue = Special Issue | pages = 54–58 | pmid = 8593194 | title = The clinical effect of a stabilized stannous fluoride dentifrice on plaque formation, gingivitis and gingival bleeding: a six-month study. ]
For discussion of Stannate compounds (SnO32
−) see Stannate. For Stannite (SnO2 −) see Stannite. See also Stannous hydroxide(Sn(OH)2), Stannic acid(Stannic Hydroxide - Sn(OH)4), Tin dioxide(Stannic Oxide - SnO2), Tin(II) oxide(Stannous Oxide - SnO), Tin(II) chloride(SnCl2), Tin(IV) chloride(SnCl4)
"See also "
Tin is the element with the greatest number of stable isotopes (ten), which is probably related to the fact that 50 is a "magic number" of protons. 28 additional unstable isotopes are known, including the "doubly magic" tin-100 (100Sn) (discovered in 1994). [cite journal | author=Phil Walker | title=Doubly Magic Discovery of Tin-100 | journal=Physics World | volume=7 | issue=June | year=1994 |url=http://physicsworldarchive.iop.org/index.cfm?action=summary&doc=7%2F6%2Fphwv7i6a24%40pwa-xml&qt= ]
Tin plays no known natural biological role in humans, and possible health effects of tin are a subject of dispute. Tin itself is not toxic but most are.
Triorganotins are very toxic. Tri-"n"-alkyltins are
phytotoxicand depending on the organic groups, they can be powerful bactericides and fungicides. Other triorganotins are used as miticides and acaricides.
International Tin Council
Cassiterides(the mythical Tin Islands)
Whisker (metallurgy)(tin whiskers)
* [http://periodic.lanl.gov/elements/50.html Los Alamos National Laboratory: Tin]
* [http://www.webelements.com/webelements/elements/text/Sn/index.html WebElements.com – Tin]
* [http://www.theodoregray.com/PeriodicTable/Elements/050/index.s7.html Theodore Gray's Wooden Periodic Table Table] : Tin samples and castings
* [http://www.basemetals.com/html/sninfo.htm Base Metals: Tin]
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