Tin is a chemical element
with the symbol
Sn (from lstannum
}) and atomic number
50. Tin is a silvery metal that characteristically has a faint yellow hue. Tin, like indium
, is soft enough to be cut without much force. When a bar of tin is bent, the so-called “tin cry
” can be heard as a result of twinning
in tin crystals; this trait is shared by indium
, and frozen mercury
. Pure tin after solidifying keeps a mirror-like appearance similar to most metals. However, in most tin alloy
s (such as pewter
), the metal solidifies with a dull gray color. Tin is a post-transition metal
in group 14
of the periodic table of elements
. It is obtained chiefly from the mineral cassiterite
, which contains stannic oxide
. Tin shows a chemical similarity to both of its neighbors in group 14, germanium
, and has two main oxidation state
s, +2 and the slightly more stable +4. Tin is the 49th most abundant element on Earth and has, with 10 stable isotopes, the largest number of stable isotope
s in the periodic table, thanks to its magic number
of protons. It has two main allotropes
: at room temperature, the stable allotrope is β-tin, a silvery-white, malleable
metal, but at low temperatures, it transforms into the less dense grey α-tin, which has the diamond cubic
structure. Metallic tin does not easily oxidize
The first tin alloy used on a large scale was bronze
, made of tin and copper
, from as early as 3000 BC. After 600 BC, pure metallic tin was produced. Pewter
, which is an alloy of 85–90% tin with the remainder commonly consisting of copper
, and lead, was used for flatware
from the Bronze Age
until the 20th century. In modern times, tin is used in many alloys, most notably tin / lead soft solder
s, which are typically 60% or more tin, and in the manufacture of transparent, electrically conducting films of indium tin oxide
applications. Another large application for tin is corrosion
-resistant tin plating
. Because of the low toxicity of inorganic tin, tin-plated steel is widely used for food packaging as tin cans
. However, some organotin compounds
can be almost as toxic as cyanide
Tin is a soft, malleable
and highly crystal
line silvery-white metal
. When a bar of tin is bent, a crackling sound known as the "tin cry
" can be heard from the twinning
of the crystals.
Tin melts at low temperatures of about , the lowest in group 14. The melting point is further lowered to for 11 nm particles.
β-tin (the metallic form, or white tin, BCT structure), which is stable at and above room temperature, is malleable. In contrast, α-tin (nonmetallic form, or gray tin), which is stable below , is brittle
. α-tin has a diamond cubic crystal structure
, similar to diamond
. α-tin has no metallic properties at all because its atoms form a covalent structure in which electrons cannot move freely. It is a dull-gray powdery material with no common uses other than a few specialized semiconductor
These two allotrope
s, α-tin and β-tin, are more commonly known as ''gray tin'' and ''white tin'', respectively. Two more allotropes, γ and σ, exist at temperatures above and pressures above several GPa
. In cold conditions, β-tin tends to transform spontaneously into α-tin, a phenomenon known as "tin pest
" or "tin disease". Some unverifiable 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 over time, contributing to the defeat of the Grande Armée
, a persistent legend that probably has no background in real events.
Although the α-β transformation temperature is nominally , impurities (e.g. Al, Zn, etc.) lower the transition temperature well below and, on the addition of antimony
, the transformation might not occur at all, increasing the durability of the tin.
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 few elements have appreciable solid solubility in tin. Simple eutectic
systems, however, occur with bismuth
Tin becomes a superconductor
below 3.72 K
and 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.
Tin resists corrosion from water
, but can be attacked by acid
s and alkali
s. Tin can be highly polished and is used as a protective coat for other metals.
A protective oxide (passivation
) layer prevents further oxidation, the same that forms on pewter and other tin alloys. Tin acts as a catalyst
is in solution and helps to accelerate the chemical reaction.
Tin has ten stable isotopes
, with atomic masses of 112, 114 through 120, 122, and 124, the greatest number
of any element. Of these, the most abundant are 120
Sn (almost a third of all tin), 118
Sn, and 116
Sn, while the least abundant is 115
Sn. The isotopes with even mass number
s have no nuclear spin
, while those with odd have a spin of +1/2. Tin, with its three common isotopes 116
Sn, and 120
Sn, is among the easiest elements to detect and analyze by NMR spectroscopy
, and its chemical shift
s are referenced against .
[Only H, F, P, Tl and Xe have a higher receptivity for NMR analysis for samples containing isotopes at their natural abundance.]
This large number of stable isotopes is thought to be a direct result of the atomic number
50, a "magic number
" in nuclear physics. Tin also occurs in 31 unstable isotopes, encompassing all the remaining atomic masses from 99 to 139. Apart from 126Sn
, with a half-life
of 230,000 years, all the radioisotopes have a half-life of less than a year. The radioactive 100Sn
, discovered in 1994, and 132Sn
are two of the few nuclides with a "doubly magic
" nucleus: despite being unstable, having very lopsided proton–neutron ratios, they represent endpoints beyond which stability drops off rapidly. Another 30 metastable isomers
have been characterized for isotopes between 111 and 131, the most stable being 121mSn
with a half-life of 43.9 years.
The relative differences in the abundances of tin's stable isotopes can be explained by their different modes of formation in stellar nucleosynthesis
Sn through 120
Sn inclusive are formed in the ''s''-process
(slow neutron capture) in most star
s and hence they are the most common isotopes, while 122
Sn and 124
Sn are only formed in the ''r''-process
(rapid neutron capture) in supernovae
and are less common. (The isotopes 117
Sn through 120
Sn also receive contributions from the ''r''-process.) Finally, the rarest proton-rich isotopes, 112
Sn, and 115
Sn, cannot be made in significant amounts in the ''s''- or ''r''-processes and are considered among the p-nuclei
, whose origins are not well understood yet. Some speculated mechanisms for their formation include proton capture
as well as photodisintegration
, although 115
Sn might also be partially produced in the ''s''-process, both directly, and as the daughter of long-lived 115In
The word ''tin'' is shared among Germanic languages
and can be traced back to reconstructed Proto-Germanic
s include German
. It is not found in other branches of Indo-European
, except by borrowing
from Germanic (e.g., Irish
name originally meant an alloy of silver and lead, and came to mean 'tin' in the 4th century—the earlier Latin word for it was , or "white lead". apparently came from an earlier (meaning the same substance),
the origin of the Romance
terms for ''tin''.
The origin of / is unknown; it may be pre-Indo-European
The speculates on the contrary that is derived from (the ancestor of) Cornish
, and is evidence that Cornwall
in the first centuries AD was the main source of tin.
Tin extraction and use can be dated to the beginnings of the Bronze Age around 3000 BC, when it was observed that copper
objects formed of polymetallic ores
with different metal contents had different physical properties. The earliest bronze objects had a tin or arsenic content of less than 2% and are therefore believed to be the result of unintentional alloying
due to trace metal content in the copper ore.
The addition of a second metal to copper increases its hardness, lowers the melting temperature, and improves the casting
process by producing a more fluid melt that cools to a denser, less spongy metal.
This was an important innovation that allowed for the much more complex shapes cast in closed molds
of the Bronze Age. Arsenical bronze
objects appear first in the Near East where arsenic is commonly found in association with copper ore, but the health risks
were quickly realized and the quest for sources of the much less hazardous tin ores began early in the Bronze Age. This created the demand for rare tin metal and formed a trade network that linked the distant sources of tin to the markets of Bronze Age cultures.
), the tin oxide form of tin, was most likely the original source of tin in ancient times. Other forms of tin ores are less abundant sulfide
s such as stannite
that require a more involved smelting
process. Cassiterite often accumulates in alluvial
channels as placer deposits
because it is harder, heavier, and more chemically resistant than the accompanying granite
Cassiterite is usually black or generally dark in color, and these deposits can be easily seen in river banks
. Alluvial (placer
) deposits may incidentally have been collected and separated by methods similar to gold panning
Compounds and chemistry
In the great majority of its compounds, tin has the oxidation state II or IV.
Halide compounds are known for both oxidation states. For Sn(IV), all four halides are well known: SnF4
, and SnI4
. The three heavier members are volatile molecular compounds, whereas the tetrafluoride is polymeric. All four halides are known for Sn(II) also: SnF2
, and SnI2
. All are polymeric solids. Of these eight compounds, only the iodides are colored.
(also known as stannous chloride) is the most important tin halide in a commercial sense. Illustrating the routes to such compounds, chlorine
reacts with tin metal to give SnCl4
whereas the reaction of hydrochloric acid and tin produces SnCl2
and hydrogen gas. Alternatively SnCl4
and Sn combine to stannous chloride by a process called comproportionation
+ Sn → 2 SnCl2
Tin can form many oxides, sulfides, and other chalcogenide derivatives. The dioxide SnO2
(cassiterite) forms when tin is heated in the presence of air
, which means that it dissolves in both acidic and basic solutions.
Stannates with the structure n(OH)6
sup>2−, like K2n(OH)6
are also known, though the free stannic acid H2n(OH)6
s of tin exist in both the +2 and +4 oxidation states: tin(II) sulfide
and tin(IV) sulfide
), with tin in the +4 oxidation state, is unstable. Organotin hydrides are however well known, e.g. tributyltin hydride
These compound release transient tributyl tin radicals, which are rare examples of compounds of tin(III).
compounds, sometimes called stannanes, are chemical compounds
with tin–carbon bonds. Of the compounds of tin, the organic derivatives are the most useful commercially.
[ Some organotin compounds are highly toxic and have been used as biocides. The first organotin compound to be reported was diethyltin diiodide ((C2H5)2SnI2), reported by Edward Frankland in 1849.
Most organotin compounds are colorless liquids or solids that are stable to air and water. They adopt tetrahedral geometry. Tetraalkyl- and tetraaryltin compounds can be prepared using Grignard reagents:] [
: + 4 RMgBr → + 4 MgBrCl
The mixed halide-alkyls, which are more common and more important commercially than the tetraorgano derivatives, are prepared by redistribution reactions:
: + → 2 SnCl2R2
Divalent organotin compounds are uncommon, although more common than related divalent organogermanium and organosilicon compounds. The greater stabilization enjoyed by Sn(II) is attributed to the "inert pair effect". Organotin(II) compounds include both stannylenes (formula: R2Sn, as seen for singlet carbenes) and distannylenes (R4Sn2), which are roughly equivalent to alkenes. Both classes exhibit unusual reactions.
Tin is generated via the long ''s''-process in low-to-medium mass stars (with masses of 0.6 to 10 times that of the Sun), and finally by beta decay of the heavy isotopes of indium.
Tin is the 49th most abundant element in Earth's crust, representing 2 ppm compared with 75 ppm for zinc, 50 ppm for copper, and 14 ppm for lead.
Tin does not occur as the native element but must be extracted from various ores. Cassiterite (SnO2) is the only commercially important source of tin, although small quantities of tin are recovered from complex sulfides such as stannite, cylindrite, franckeite, canfieldite, and teallite. Minerals with tin are almost always associated with granite rock, usually at a level of 1% tin oxide content.
Because of the higher specific gravity of tin dioxide, about 80% of mined tin is from secondary deposits found downstream from the primary lodes. Tin is often recovered from granules washed downstream in the past and deposited in valleys or the sea. The most economical ways of mining tin are by dredging, hydraulicking, or open pits. Most of the world's tin is produced from placer deposits, which can contain as little as 0.015% tin.
About 253,000 tonnes of tin have been mined in 2011, mostly in China (110,000 t), Indonesia (51,000 t), Peru (34,600 t), Bolivia (20,700 t) and Brazil (12,000 t). Estimates of tin production have historically varied with the dynamics of economic feasibility and the development of mining technologies, but it is estimated that, at current consumption rates and technologies, the Earth will run out of mine-able tin in 40 years. Lester Brown has suggested tin could run out within 20 years based on an extremely conservative extrapolation of 2% growth per year.
Secondary, or scrap, tin is also an important source of the metal. Recovery of tin through secondary production, or recycling of scrap tin, is increasing rapidly. Whereas the United States has neither mined since 1993 nor smelted tin since 1989, it was the largest secondary producer, recycling nearly 14,000 tonnes in 2006.
New deposits are reported in Mongolia, and in 2009, new deposits of tin were discovered in Colombia by the Seminole Group Colombia CI, SAS.
Tin is produced by carbothermic reduction of the oxide ore with carbon or coke. Both reverberatory furnace and electric furnace can be used.
Mining and smelting
The ten largest companies produced most of the world's tin in 2007.
Most of the world's tin is traded on the London Metal Exchange (LME), from 8 countries, under 17 brands.
An International Tin Council was established in 1947 to control the price of tin, until it collapsed in 1985. In 1984, an ''Association of Tin Producing Countries'' was created, with Australia, Bolivia, Indonesia, Malaysia, Nigeria, Thailand, and Zaire as members.
Price and exchanges
Tin is unique among other mineral commodities because of the complex agreements between producer countries and consumer countries dating back to 1921. The earlier agreements tended to be somewhat informal and sporadic and led to the "First International Tin Agreement" in 1956, the first of a continuously numbered series that effectively collapsed in 1985. Through this series of agreements, the International Tin Council (ITC) had a considerable effect on tin prices. The ITC supported the price of tin during periods of low prices by buying tin for its buffer stockpile and was able to restrain the price during periods of high prices by selling tin from the stockpile. This was an anti-free-market approach, designed to assure a sufficient flow of tin to consumer countries and a profit for producer countries. However, the buffer stockpile was not sufficiently large, and during most of those 29 years tin prices rose, sometimes sharply, especially from 1973 through 1980 when rampant inflation plagued many world economies.
During the late 1970s and early 1980s, the U.S. Government tin stockpile was in an aggressive selling mode, partly to take advantage of the historically high tin prices. The sharp recession of 1981–82 proved to be quite harsh on the tin industry. Tin consumption declined dramatically. The ITC was able to avoid truly steep declines through accelerated buying for its buffer stockpile; this activity required the ITC to borrow extensively from banks and metal trading firms to augment its resources. The ITC continued to borrow until late 1985 when it reached its credit limit. Immediately, a major "tin crisis" followed — tin was delisted from trading on the London Metal Exchange for about three years, the ITC dissolved soon afterward, and the price of tin, now in a free-market environment, plummeted sharply to $4 per pound and remained at that level through the 1990s.] [Carlin, James F., Jr. (1998)] The price increased again by 2010 with a rebound in consumption following the 2008–09 world economic crisis, accompanying restocking and continued growth in consumption by the world's developing economies.
Significant events affecting tin prices since 1958
London Metal Exchange (LME) is the principal trading site for tin. Other tin contract markets are Kuala Lumpur Tin Market (KLTM) and Indonesia Tin Exchange (INATIN).
The price per kg over years:
In 2018, just under half of all tin produced was used in solder. The rest was divided between tin plating, tin chemicals, brass and bronze alloys, and niche uses.
Tin has long been used in alloys with lead as solder, in amounts 5 to 70% w/w. Tin with lead forms a eutectic mixture at the weight proportion of 61.9% tin and 38.1% lead (the atomic proportion: 73.9% tin and 26.1% lead), with melting temperature of 183 °C (361.4 °F) . Such solders are primarily used for joining pipes or electric circuits. Since the European Union Waste Electrical and Electronic Equipment Directive (WEEE Directive) and Restriction of Hazardous Substances Directive came into effect on 1 July 2006, the lead content in such alloys has decreased. While lead exposure is associated with serious health problems, lead-free solder is not without its own challenges, including a higher melting point, and the formation of tin whiskers causing electrical problems. Tin pest can occur in lead-free solders, leading to loss of the soldered joint. Replacement alloys are rapidly being found, although problems of joint integrity remain.
Tin bonds readily to iron and is used for coating lead, zinc and steel to prevent corrosion. Tin-plated steel containers are widely used for food preservation, and this forms a large part of the market for metallic tin. A tinplate canister for preserving food was first manufactured in London in 1812. Speakers of British English call them "tins", while speakers of American English call them "cans" or "tin cans". One derivation of such use is the slang term "tinnie" or "tinny", meaning "can of beer" in Australia. The tin whistle is so called because it was first mass-produced in tin-plated steel. Copper cooking vessels such as saucepans and frying pans are frequently lined with a thin plating of tin, since the combination of acid foods with copper can be toxic.
Tin in combination with other elements forms a wide variety of useful alloys. Tin is most commonly alloyed with copper. Pewter is 85–99% tin; bearing metal has a high percentage of tin as well. Bronze is mostly copper (12% tin), while addition of phosphorus gives phosphor bronze. Bell metal is also a copper–tin alloy, containing 22% tin. Tin has sometimes been used in coinage; for example, it once formed a single-digit percentage (usually five percent or less) of American and Canadian pennies. Because copper is often the major metal in such coins, sometimes including zinc, these could be called bronze and/or brass alloys.
The niobium–tin compound Nb3Sn is commercially used in coils of superconducting magnets for its high critical temperature (18 K) and critical magnetic field (25 T). A superconducting magnet weighing as little as two kilograms is capable of the magnetic field of a conventional electromagnet weighing tons.
A small percentage of tin is added to zirconium alloys for the cladding of nuclear fuel.
Most metal pipes in a pipe organ are of a tin/lead alloy, with 50/50 being the most common composition. The proportion of tin in the pipe defines the pipe's tone, since tin has a desirable tonal resonance. When a tin/lead alloy cools, the lead phase solidifies first, then when the eutectic temperature is reached the remaining liquid forms the layered tin/lead eutectic structure, which is shiny and the contrast with the lead phase produces a mottled or spotted effect. This metal alloy is referred to as spotted metal. Major advantages of using tin for pipes include its appearance, its workability, and resistance to corrosion.
The oxides of indium and tin are electrically conductive and transparent, and are used to make transparent electrically conducting films with applications in Optoelectronics devices such as liquid crystal displays.
Punched tin-plated steel, also called pierced tin, is an artisan technique originating in central Europe for creating housewares that are both functional and decorative. Decorative piercing designs exist in a wide variety, based on local tradition and the artisan's personal creations. Punched tin lanterns are the most common application of this artisan technique. The light of a candle shining through the pierced design creates a decorative light pattern in the room where it sits. Lanterns and other punched tin articles were created in the New World from the earliest European settlement. A well-known example is the Revere lantern, named after Paul Revere.
Before the modern era, in some areas of the Alps, a goat or sheep's horn would be sharpened and a tin panel would be punched out using the alphabet and numbers from one to nine. This learning tool was known appropriately as "the horn". Modern reproductions are decorated with such motifs as hearts and tulips.
In America, pie safes and food safes were in use in the days before refrigeration. These were wooden cupboards of various styles and sizes – either floor standing or hanging cupboards meant to discourage vermin and insects and to keep dust from perishable foodstuffs. These cabinets had tinplate inserts in the doors and sometimes in the sides, punched out by the homeowner, cabinetmaker or a tinsmith in varying designs to allow for air circulation while excluding flies. Modern reproductions of these articles remain popular in North America.
Window glass is most often made by floating molten glass on molten tin (float glass), resulting in a flat and flawless surface. This is also called the "Pilkington process".
Tin is also used as a negative electrode in advanced Li-ion batteries. Its application is somewhat limited by the fact that some tin surfaces catalyze decomposition of carbonate-based electrolytes used in Li-ion batteries.
Tin(II) fluoride is added to some dental care products as stannous fluoride (SnF2). Tin(II) fluoride can be mixed with calcium abrasives while the more common sodium fluoride gradually becomes biologically inactive in the presence of calcium compounds. It has also been shown to be more effective than sodium fluoride in controlling gingivitis.
Tin is also used as a target to create laser induced plasmas which act as the light source for Extreme ultraviolet lithography.
Of all the chemical compounds of tin, the organotin compounds are most heavily used. Worldwide industrial production probably exceeds 50,000 tonnes.
The major commercial application of organotin compounds is in the stabilization of PVC plastics. In the absence of such stabilizers, PVC would otherwise rapidly degrade under heat, light, and atmospheric oxygen, resulting in discolored, brittle products. Tin scavenges labile chloride ions (Cl−), which would otherwise initiate loss of HCl from the plastic material.
Typical tin compounds are carboxylic acid derivatives of dibutyltin dichloride, such as the dilaurate.
Some organotin compounds are relatively toxic, with both advantages and problems. They are used for biocidal properties as fungicides, pesticides, algaecides, wood preservatives, and antifouling agents.
[ Tributyltin oxide is used as a wood preservative. Tributyltin is also used for various industrial purposes such as slime control in paper mills and used for disinfection of the circulating industrial cooling waters.Tributyltin was used as additive for ship paint to prevent growth of marine organisms on ships, with use declining after organotin compounds were recognized as persistent organic pollutants with an extremely high toxicity for some marine organisms (the dog whelk, for example). The EU banned the use of organotin compounds in 2003, while concerns over the toxicity of these compounds to marine life and damage to the reproduction and growth of some marine species] (some reports describe biological effects to marine life at a concentration of 1 nanogram per liter) have led to a worldwide ban by the International Maritime Organization. Many nations now restrict the use of organotin compounds to vessels greater than long. [ The persistence of tributyltin in the aquatic environment is dependent upon the nature of the ecosystem.] Because of this persistence and for it being an additive in ship paint, high concentrations of tributyltin have been found in marine sediments located near naval docks. Tributyltin has also been used as a biomarker for imposex in neograstropods with at least 82 known species. With the extremely high levels of TBT in the local inshore areas, due to shipping activities, the shellfish had an adverse effect. Imposex is the imposition of male sexual characteristics on female specimens where they will start to grow a penis and a pallial vans deferens. Having high levels of TBT within your system is deadly because it can damage the endocrine glands, the reproductive and central nervous systems, bone structure and gastrointestinal tract of mammals. Not only does tributyltin affect mammals, it also has an effect on sea otters, whales, dolphins, and humans as well.
Some tin reagents are useful in organic chemistry. In the largest application, stannous chloride is a common reducing agent for the conversion of nitro and oxime groups to amines. The Stille reaction couples organotin compounds with organic halides or pseudohalides.
Tin forms several inter-metallic phases with lithium metal, making it a potentially attractive material for battery applications. Large volumetric expansion of tin upon alloying with lithium and instability of the tin-organic electrolyte interface at low electrochemical potentials are the greatest challenges to employment in commercial cells. The problem was partially solved by Sony. Tin inter-metallic compound with cobalt and carbon has been implemented by Sony in its Nexelion cells released in the late 2000s. The composition of the active material is approximately Sn0.3Co0.4C0.3. Recent research showed that only some crystalline facets of tetragonal (beta) Sn are responsible for undesirable electrochemical activity.
Cases of poisoning from tin metal, its oxides, and its salts are almost unknown. On the other hand, certain organotin compounds are almost as toxic as cyanide.
[Graf, G. G. (2000) "Tin, Tin Alloys, and Tin Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH, Weinheim ]
Exposure to tin in the workplace can occur by inhalation, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for tin exposure in the workplace as 2 mg/m3 over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has determined a recommended exposure limit (REL) of 2 mg/m3 over an 8-hour workday. At levels of 100 mg/m3, tin is immediately dangerous to life and health.
* Cassiterides (the mythical Tin Islands)
* List of countries by tin production
* Tin pest
* Tin mining in Britain
* Whisker (metallurgy) (tin whiskers)
at ''The Periodic Table of Videos'' (University of Nottingham)
Theodore Gray's Wooden Periodic Table Table
Tin samples and castings
Tin (USD cents per kg)
Category:Native element minerals