TIN

Tin

About Tin :

Tin is a silvery-white metal that’s obtained mainly from the mineral cassiterite. The element is present in the igneous rocks of Earth’s crust to the extent of about 0.001 percent, which is scarce but not rare. Cosmically, tin is a product of neutron absorption. Its richness in stable isotopes is remarkable. The symbol Sn for tin is an abbreviation of the Latin word for tin, stannum. Tin (Sn), a chemical element belonging to the carbon family, Group 14 of the periodic table. It is a soft, silvery white metal with a bluish tinge, is malleable, ductile and not easily oxidized in air; it’s also lightweight, durable and quite resistant to corrosion. The origins of tin are lost in ancient times. Bronzes, which are copper–tin alloys, were used by humans in prehistory long before pure tin metal itself was derived. Bronzes were common in early Mesopotamia, the Indus valley. Much of the tin used by the early Mediterranean peoples. Tin occurs in grains of the native metal but chiefly as stannic oxide, SnO2, in the mineral cassiterite, the only tin mineral of commercial significance. The metal is obtained by reduction (removal of the oxygen) with coal or coke in smelting furnaces. In other words, it is obtained commercially by reducing the ore with coal in a furnace.

No high-grade deposits are known. A niobium-tin alloy is used for superconducting magnets.

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Tin is nontoxic, ductile, malleable, and adapted to all kinds of cold-working, such as rolling, spinning, and extrusion. The colour of pure tin is retained during exposure because a thin, invisible, protective film of stannic oxide is formed spontaneously by reaction with the oxygen of the air. The low melting point of tin and its firm adhesion to clean surfaces of iron, steel, copper, and copper alloys facilitate its use as an oxidation-resistant coating material. A soft, pliable metal. Below 13°C it slowly changes to a powder form.

Such qualities make tin a good candidate for use in solder, as well as tinplate, chemicals, brass and bronze and other niche areas. Tin is widely used for plating steel cans used as food containers, in metals used for bearings, and in solder.

Uses of Tin :

  • Tin-plating of iron protects the latter from corrosion. It takes a high polish and is used to coat other metals to prevent eroding, such as in tin cans, which are made of tin-coated steel.
  • Tin piping and valves maintain purity in water and beverages.
  • Molten tin is the base for (float) plate-glass production.
  • Tin plus the element niobium makes a superconductive metal used for wire. A tin/lead alloy is used to make solder. A crystalline alloy with niobium is a superconductor at temperatures as high as 18 K (−427 °F) and retains this property in very strong magnetic fields.
  • Tin fluoride and tin pyrophosphate, in which tin is in the +2 oxidation state, are used in dentifrices.
  • Organic tin compounds act as stabilizers in certain plastics and as wood preservatives. Zinc stannate (Zn2SnO4) is a fire-retardant used in plastics.
  • The most important tin salt used is tin(II) chloride, which is used as a reducing agent and as a mordant for dyeing calico and silk.
  • Tin(IV) oxide is used for ceramics and gas sensors. Some tin compounds have been used as anti-fouling paint for ships and boats, to prevent barnacles. However, even at low levels these compounds are deadly to marine life, especially oysters. Its use has now been banned in most of the countries.
  • The end product, called tinplate, is highly suitable for roofing (and walling) material. in plating is the process of coating metals such as iron and steel with tin to create a lightweight, corrosion-resistant finish.

Properties of Tin

Formula Sn
Atomic number 50
Atomic weight 118.69
Hardness 1.5 - 2.0 mohs
Specific gravity 7.31
Tenacity Malleable
Melting point 505.08 K (231.93 °C, 449.47 °F)
Boiling point 2875 K (2602 °C, 4716 °F)
Electronegativity pauling scale 1.96
Atomic Radius Empirical 140pm
Covalent Radius 139±4 pm
Thermal Expansion 22.0 µm/(m·K) (at 25 °C)
Thermal conductivity 66.8 W/(m·K)
Electrical resistivity 115 nΩ·m (at 0 °C)
Young's modulus 50 Gpa
Shear modulus 18 Gpa
Bulk Modulus 58 Gpa
Poisson ratio 0.36
Brinell Hardness 50–440 MPa