TIN

Tin has been known since ancient times, and has characteristics feature of superconductor. Tin belongs to the carbon family and is widely used in container to form protective layer.

Discovery and History

Tin has been used since ancient civilization, mostly in the form of alloy as early as 3000 BC. After 600BC, Pewter purified metallic tin alloy which contained 85-90% tin and consisted of copper, antimony and lead. It was used for making flatware (tableware). Chinese mined tin in the province of Yunnan in about 700 BC. Mediterranean peoples from British Isles (group of islands) were mining tin around 300-200 BC. British scientist Robert Boyle published his experimental description on the oxidation of tin in 1673. The symbol of Tin ‘’Sn’’ was derived from its Latin word Stannum [1]. Tin was used in making toys in early 1800s.

Periodic Table Classification	Group 14 Period 5
State at 20C	Solid
Color	Silvery white
Electron Configuration	[Kr] 4d5 5s1
Electron Number	50
Proton Number	50
Electron Shell	2, 8, 18, 18, 4
Density	7.31 g.cm-3 at 20°C
Atomic number	50
Atomic Mass	118.71 g.mol -1
Electronegativity according to Pauling	1.96

Occurrence

Tin is present in igneous rocks of earth’s crust. It is the 49^th most abundant element on Earth. Tin is not a native element, and mostly extracted from its ore Cassiterite (SnO₂), reduced with coal in a furnace [2]. Tin is found in the ‘’tin belt’’ which stretches from South China, Thailand, Burma to Malaysia and then Indonesia.

Physical characteristics

Tin is soft, pliable and ductile in nature. Tin retains its color due to formation of stannic oxide protective film on the surface via reaction with oxygen of the air. Tin is used as oxidation resistant coating material due to its low melting point. Tin has atomic number 50 and its atomic weight is 118.69. Tin has two allotropes forms: β-tin is silvery white soft metal, and at low temperature it transforms into less dense α- tin metal which is gray in color and has diamond cubic structure [2]. Tin melts at low temperature about 231⁰ C. Its boiling point is very high, about 2260⁰C. Tin produce a distinct sound, known as the ‘Tin cry’’ when it is bent. During winter, it changes from one allotropic form to another [3].

Chemical characteristics

Tin is resistant to corrosion and at room temperature it is unaffected by water and oxygen. But with increase in temperature, tin reacts with oxygen and forms oxides. Tin does not react with dilute acids but is easily dissolved in concentrated acids. Tin reacts with halogens to form compounds like tin chloride and tin bromide. When oxygen is present in a solution, tin act as a catalyst in the chemical reaction. Tin compounds usually occur in the divalent state (Sn²⁺) and tetravalent state (Sn⁴⁺). Tin forms halides, Sn (IV) halides include, SnF_4,SnCl₄, SnBr₄ and SnI₄. Tetrafluoride is polymeric (poly means many, mer means parts), and others compounds are volatile. Sn (II) halides are SnF_2,SnCl₂, SnBr₂ and SnI₂. These all are polymeric solids. Tin forms many oxides. SnO₂ is amphoteric in nature and sulfides of tins exits in both +2 and +4 states.

Uses and Significance

Tin is used in alloys with lead as solders to attach metal wires with electrical devices.
Tin is also used in the manufacturing of various alloys such as, bronze, pewter, phosphor bronze.
Tin oxide is used for making ceramic bodies opaque.
Organic tin compounds are used as biocides and fungicides.
Tin is helpful to coat other metals to prevent them from corrosion.
For the prevention of barnacles in ships and boats, tin compounds are used as anti-fouling (a compound that retards the growth of algae and marine organisms).
Tin chloride is used as a powerful reducing agent.
Steel container plated with tin is used for preservation of food.
Tin powder is also used in the making of paper, inks and spray.
Electroplating of tin is very common
Tin foil is also used to wrap candies tobacco etc.
Tin chromate is used as coloring agent for porcelain.
Tin valve and piping is helpful in maintaining purity in water.
Tin salt sprays are used to produce electrically conductive coating on glass.
Tin is used in making various toothpaste.
It is used in various textiles industries.

Health effects

Tin is non -toxic element but some compounds of tin are toxic in nature. Mostly, using tin utensil can have adverse effects on health. Tin inhalation can cause problem such as nausea, diarrhea, vomiting and cramps [4].

Isotopes of Tin

Tin have ten stable isotopes. The isotopes contain atomic masses of 112, 114 to 120, 122 and 124. The most abundant isotopes are ¹²⁰Sn, ¹¹⁸ Sn and ¹¹⁶Sn, and least abundant isotope is ¹¹⁵Sn. Tin also has 29 unstable isotopes with atomic masses from 99 to 137. ¹²⁶Sn isotopes has half -life of 230,000 years.