Difference between revisions of "Tin" - New World Encyclopedia

Vapor pressure
50	indium ← tin → antimony
	periodic table
General
Name, Symbol, Number	tin, Sn, 50
Chemical series	poor metals
Group, Period, Block	14, 5, p
Appearance	silvery lustrous gray ;
Atomic mass	118.710(7) g/mol
Electron configuration	[Kr] 4d10 5s2 5p2
Electrons per shell	2, 8, 18, 18, 4
Physical properties
Phase	solid
Density (near r.t.)	(white) 7.265 g/cm³
Density (near r.t.)	(gray) 5.769 g/cm³
Liquid density at m.p.	6.99 g/cm³
Melting point	505.08 K; (231.93 °C, 449.47 °F)
Boiling point	2875 K; (2602 °C, 4716 °F)
Heat of fusion	(white) 7.03 kJ/mol
Heat of vaporization	(white) 296.1 kJ/mol
Heat capacity	(25 °C) (white); 27.112 J/(mol·K)
Atomic properties
Crystal structure	tetragonal
Oxidation states	4, 2; (amphoteric oxide)
Electronegativity	1.96 (Pauling scale)
Ionization energies; (more)	1st: 708.6 kJ/mol
	2nd: 1411.8 kJ/mol
	3rd: 2943.0 kJ/mol
Atomic radius	145 pm
Atomic radius (calc.)	145 pm
Covalent radius	141 pm
Van der Waals radius	217 pm
Miscellaneous
Magnetic ordering	no data
Electrical resistivity	(0 °C) 115 nΩ·m
Thermal conductivity	(300 K) 66.8 W/(m·K)
Thermal expansion	(25 °C) 22.0 µm/(m·K)
Speed of sound (thin rod)	(r.t.) (rolled) 2730 m/s
Speed of sound (thin rod)	(r.t.) 50 m/s
Shear modulus	18 GPa
Bulk modulus	58 GPa
Poisson ratio	0.36
Mohs hardness	1.5
Brinell hardness	51 MPa
CAS registry number	7440-31-5
Notable isotopes

Revision as of 05:51, 24 November 2006

This article is about the metallic chemical element. For other uses of the term, see Tin (disambiguation).

The alchemical symbol for tin

Tin ore

Tin (chemical symbol Sn, atomic number 50) is a silvery, malleable metal that is not easily oxidized in air and resists corrosion. It is found in many alloys and is used to coat other metals to prevent corrosion. Tin is obtained chiefly from the mineral cassiterite, in which it occurs as an oxide.

Occurrence

Tin (Anglo-Saxon tin, Latin stannum) is mined in about 35 countries throughout the world. Nearly every continent has an important tin-mining country. This metal is a relatively scarce element, with an abundance in the Earth's crust of about 2 parts per million (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; at least one-half comes from Southeast Asia. Tasmania hosts some important deposits of historical importance, most importantly Mount Bischoff and Renison Bell.

The only mineral of commercial importance as a source of tin is cassiterite (SnO₂). Tin is produced by reducing the ore with coal in a reverberatory furnace. In addition, small quantities of tin are recovered from complex sulfides such as stannite, cylindrite, franckeite, canfieldite, and teallite. Secondary (scrap) tin is also an important source of the metal.

History

Tin is one of the earliest metals known and was used as a component of bronze from antiquity. Given its hardening effect on copper, tin was used in bronze implements as early as 3,500 B.C.E. Tin mining is believed to have started in Cornwall and Devon (especially Dartmoor) in classical times, and a thriving tin trade developed with civilizations of the Mediterranean. The pure metal, however, was not used until about 600 B.C.E. The last Cornish tin mine, at South Crofty near Camborne, closed in 1998, bringing 4,000 years of mining in Cornwall to an end.

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.

In modern times, the word "tin" is often (improperly) used as a generic phrase for any silvery metal that comes in thin sheets. Most everyday objects that are commonly called tin, such as aluminum foil, beverage cans, and tin cans, are actually made of steel or aluminum, although tin cans do have 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 thin coating of tin to inhibit rust.

Notable characteristics

Tin is located in group 14 (former group 4A) of the periodic table, between germanium and lead. In addition, it lies in period 5, between indium and antimony. It is sometimes known as a "poor metal," a name given to metals that come after the transition metals in the periodic table.

This silvery-white metal is malleable, ductile, and highly crystalline. When a bar of tin is bent, a strange crackling sound known as the "tin cry" is produced, caused by breakage of the crystals. The metal resists corrosion from distilled water, seawater, and soft, tap water, but it can be attacked by strong acids, alkalis, and acid salts. It acts as a catalyst when oxygen is in solution and helps accelerate chemical attack.

When heated in the presence of air, tin forms the dioxide (SnO₂). The dioxide, in turn, is feebly acidic and forms stannate (SnO₃^-2) salts with basic oxides. Tin can be highly polished and is used as a protective coat for other metals, to prevent corrosion or other chemical action. This metal combines directly with chlorine and oxygen and displaces hydrogen from dilute acids. It is malleable at ordinary temperatures but is brittle when heated.

Isotopes

Tin has 10 stable isotopes, making it the element with the highest number of stable isotopes. Many additional, unstable isotopes are known.

Allotropes

Solid tin has two allotropes at normal pressure. At low temperatures, it exists as gray or alpha tin, which has a cubic crystal structure, similar to that of silicon and germanium. When warmed above 13.2 °C, it changes into white or beta tin, which is metallic and has a tetragonal structure. When cooled, it slowly returns to the gray form, a phenomenon called tin pest or tin disease. This transformation, however, is affected by impurities such as aluminum and zinc and can be prevented from occurring by the addition of antimony or bismuth.

Compounds

Tin(II) chloride, or stannous chloride (SnCl₂): It is a white, crystalline solid that forms a stable dihydrate. It can dissolve in less than its own mass of water without apparent decomposition, but as the solution is diluted, hydrolysis occurs to form an insoluble, basic salt. Therefore, to maintain tin(II) chloride as a clear solution, hydrochloric acid must be added. A solution of this chloride containing a little hydrochloric acid is used for the tin-plating of steel, to make tin cans. It is also widely used as a reducing agent, such as for silvering mirrors, where silver metal is deposited on glass. In addition, it is used as a catalyst in the production of the plastic polylactic acid (PLA).

For discussion of Stannate compounds (SnO₃^2-) 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)

Applications

Tin bonds readily to iron, and has been used for coating lead or 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. 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 whistle is so called because it was first mass-produced in tin-plated steel.

Other uses:

Some important tin alloys are: bronze, bell metal, Babbitt metal, die casting alloy, pewter, phosphor bronze, soft solder, and White metal.
The most important salt formed is stannous chloride, which has found use as a reducing agent and as a mordant in 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.
Most metal pipes in a pipe organ are made of varying amounts of a tin/lead alloy, with 50% / 50% being the most common. When this alloy cools, the lead cools slightly faster and makes a mottled or spotted effect. This metal alloy is refered to as spotted metal.
Window glass is most often made via floating molten glass on top of molten tin (creating float glass) in order to make a flat surface (this is called the "Pilkington process").
Tin is one of the two basic elements used since the Rennaisance in the manufacture of organ pipes (the other being lead). The amount of tin in the pipe defines the pipe's tone, tin being the most tonally resonant of all metals.
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 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 becomes a superconductor below 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 electromagnet weighing tons.

Biologic effects of organic tin compounds

The small amount of tin found in canned foods is not harmful to humans. Certain organic tin compounds, such as triorganotins, are toxic and are used as industrial fungicides and bactericides.

References
ISBN links support NWE through referral fees

Los Alamos National Laboratory – Tin
N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990.
The Merck Index, 7th edition, Merck & Co, Rahway, New Jersey, USA, 1960.
A. F. Wells, 'Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
J. March, Advanced Organic Chemistry, 4th ed., p. 723, Wiley, New York, 1992.

External links

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@@ Line 78: / Line 78: @@
 == Notable characteristics ==
-Tin is a malleable, ductile, highly [[crystal]]line, 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 breaking of the crystals. This metal resists corrosion from [[distilled]], sea and soft [[tap water]], but can be attacked by strong [[acid]]s, [[alkali]]s, and by [[acid salt]]s. Tin acts as a [[catalyst]] when [[oxygen]] is in solution and helps accelerate chemical attack.
+Tin is located in group 14 (former group 4A) of the [[periodic table]], between [[germanium]] and [[lead]]. In addition, it lies in period 5, between [[indium]] and [[antimony]]. It is sometimes known as a "[[poor metal]]*," a name given to metals that come after the [[transition metal]]s in the periodic table.
-Tin forms the dioxide SnO<sub>2</sub> when it is heated in the presence of [[air]]. SnO<sub>2</sub>, in turn, is feebly acidic and forms stannate (SnO<sub>3</sub><sup>-2</sup>) salts with [[Base (chemistry)|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 [[chlorine]] and oxygen and displaces [[hydrogen]] from dilute acids. Tin is malleable at ordinary temperatures but is brittle when it is heated.
+This silvery-white metal is malleable, ductile, and highly [[crystal]]line. When a bar of tin is bent, a strange crackling sound known as the "tin cry" is produced, caused by breakage of the crystals. The metal resists corrosion from [[distilled]]* water, seawater, and soft, [[tap water]]*, but it can be attacked by strong [[acid]]s, [[alkali]]s, and [[acid salt]]*s. It acts as a [[catalyst]] when [[oxygen]] is in solution and helps accelerate chemical attack.
+When heated in the presence of [[air]], tin forms the dioxide (SnO<sub>2</sub>). The dioxide, in turn, is feebly acidic and forms stannate (SnO<sub>3</sub><sup>-2</sup>) salts with [[Base (chemistry)|basic]] oxides. Tin can be highly polished and is used as a protective coat for other metals, to prevent corrosion or other chemical action. This metal combines directly with [[chlorine]] and oxygen and displaces [[hydrogen]] from dilute acids. It is malleable at ordinary temperatures but is brittle when heated.
 === Isotopes ===
-Tin is the element with the greatest number of stable isotopes (ten). 28 additional unstable isotopes are known.
+Tin has 10 stable [[isotope]]s, making it the element with the highest number of stable isotopes. Many additional, unstable isotopes are known.
 === Allotropes ===
-Solid tin has two [[allotrope]]s at normal pressure.  At low temperatures it exists as ''gray'' or alpha tin, which has a cubic [[crystal structure]] similar to [[silicon]] and [[germanium]].  When warmed above 13.2 °[[Celsius|C]] it changes into ''white'' or beta tin, which is metallic and has a tetragonal structure.  It slowly changes back to the gray form when cooled, which is called the ''[[tin pest]]'' or ''tin disease''.  However, this transformation is affected by impurities such as [[aluminium]] and [[zinc]] and can be prevented from occurring through the addition of [[antimony]] or [[bismuth]].
+Solid tin has two [[allotrope]]s at normal pressure. At low temperatures, it exists as ''gray'' or alpha tin, which has a cubic [[crystal]] structure, similar to that of [[silicon]] and [[germanium]]. When warmed above 13.2 °C, it changes into ''white'' or beta tin, which is metallic and has a tetragonal structure. When cooled, it slowly returns to the gray form, a phenomenon called ''[[tin pest]]*'' or ''tin disease''. This transformation, however, is affected by impurities such as [[aluminum]] and [[zinc]] and can be prevented from occurring by the addition of [[antimony]] or [[bismuth]].
 ==Compounds==
@@ Line 117: / Line 119: @@
 == Biologic effects of organic tin compounds==
-The small amount of tin that is found in canned foods is not harmful to humans. Certain organic tin compounds, [[organotin]], such as triorganotins (see [[tributyltin oxide]]) are toxic and are used as industrial [[fungicide]]s and [[bactericide]]s.
+The small amount of tin found in canned foods is not harmful to humans. Certain organic tin compounds, such as triorganotins, are toxic and are used as industrial [[fungicide]]s and [[bactericide]]s.
 ==See also==