|
History and Production
Derived from Anglo-Saxon. The symbol was derived from the Latin Stannum. The metal is known since ancient times, dated as far back as 3500 BC. Bronze tools containing about 10-15% tin alloyed with copper have been found in Ur.
The metal is readily extracted from the ores such as cassiterite (SnO2) by heating with coal. The resulting impure molten tin is then stirred in the presence of oxygen in order to oxidize the iron that may present in the ore.
It is used as coatings to prevent corrosion and in food preservation as in 'tin cans'. Tin is an important components for a variety of alloys: with lead, it is used to make solder and organ pipes; with small amount of antimony and copper
to make pewters with copper to make bronze.
Physical Data
It is a silvery-white metal with a highly crystalline structure. It exists in two allotropic forms which changes from gray, or a tin to white or b tin at 13.2°C, a process that is called a 'tin pest'.
Tin occurs mainly as the ore cassiterite in nature.
Interatomic distance: 281 pm (gray tin)
Melting point: 231.93°C
Boiling point: 2602°C
Thermal conductivity/Wm-1K-1: 66.6 (a, 27°C)
Density/kgm-3: 5750 (a at 25°C), 7310 (b at 25°C), 6973 (m.p.)
Standard Thermodynamic Data (atomic gas)
Enthalpy of formation: 301.2 kJ/mol
Gibbs free energy of formation: 266.2 kJ/mol
Entropy: 168.5 J/mol K
Heat capacity: 21.3 J/mol K
Electronic data
Electronic configuration: [Kr] 4d10 5s2 5p2
Term symbol: 3P0
Electron affinity: 107.2982 kJ/mol Electronegativity (Pauline): 1.96
Ionization energy (first, second, third): 708.579, 1411.80, 2943.06 kJ/mol
Chemical properties
Ordinary white tin is not attacked by air or water at room temperature. On heating in air it forms tin(IV) oxide, SnO2. It is easily attacked by halogens to give the
corresponding tetrahalide. It also dissolves readily in concentrated hydrochloric acid to give tin(II) chloride, SnCl2.
Test for tin:
The charcoal block test gives metallic beads with a yellow (hot) or white (cold) incrustation.
Test for tin(II) ion:
(1) Hydrogen sulfide gives brown precipitate of tin(II) sulfide, soluble in yellow ammonium sulfide.
(2) Mercury(II) chloride is reduced to a white precipitate of mercury(I) chloride and then to metallic mercurry.
Test for tin(IV) ion:
(1) Hydrogen sulfide gives a yellow precipitate of tin(IV) sulfide, soluble in colorless or yellow ammonium sulfide.
(2) Mercury(II) chloride gives no precipitate.
| 
