Short Answer Type
Long Answer TypeHow do elements of group 14 occur in nature? Give their uses.
Occurrence of Group 14 elements:
Occurrence of Carbon and its uses. Carbon is one of the most important element since it is an essential constituent of most of the compounds found in plants and animals. It occurs:
(i) In native state. Carbon occurs in native state as diamond, graphite and coal.
(ii) In combined state.
(a) It occurs in all living organisms, plants and animal body as proteins, carbohydrates, fats and other complex compounds.
(b) Atmosphere. It is present as CO2 to the extent of 0.03 percent.
(c) Hydrocarbon. It occurs as hydrocarbons in marsh gas, petroleum, paraffin, vaseline, paper, cloth etc.
(d) Minerals. It occurs widely in minerals such as chalk, marble, kanker, lime stone which are different varieties of calcium carbonate ; magnesite, MgCO3 ; dolomite, MgCO3. CaCO3 ; spathic ore of iron, FeCO3 ; zinc carbonate ZnCO3, etc.
Uses: (i) Silicon is used in the manufacture of certain alloys as ferrosilicon, silicon bronze, manganese silicon bronze etc.
(ii) Very high purity silicon is used as semi conductor in transistors.
(iii) Silicon when added to steel, increases its resistance to the attack by acids.
Occurrence of Tin and its uses:
Occurrence. Tin occurs in free state at some places but occurs widely in a number of minerals e.g. sulphide ores of copper, zinc and iron. The most common ore of tin is tin stone or cassiterite, SnO2
Uses. Tin is used:
(i) in tinning brass untensils,
(ii) in the manufacture of alloys (Bronze, Gun metal, Solders etc.),
(iii) in the form of tin foil for wrapping cigarettes,
(iv) as tin amalgam in making mirrors.
Occurrence of Lead and its uses:
Occurrence. Lead is found in native state in small traces. It is found largely in the combined state.
The important minerals of lead are:
(i) Galena: lead sulphide (PbS)
(ii)Cerussite: lead carbonate (PbCO3)
(iii) Anglesite: lead sulphate (PbSO4)
(iv) Crocoisite: lead chromate (PbCrO4).
Uses. It is used:
(i) in making cable coverings,
(ii) in making bullets, shots and lead accumulators,
(iii) in marking lead chambers for sulphuric acid plant,
(iv) in making tetraethyl lead, Pb(C2H5)4, which is used as an anti knocking agent in petrol,
(v) in making various lead alloys such as solder, type metal and pewter.
Short Answer TypeLong Answer TypeDiscuss the characteristics of group 14 elements in terms of:
(i) Atomic radius
(ii) Ionisation enthalpy
(iii) Electropositive character
(iv) Melting and boiling points.
Short Answer TypeExplain why is there a phenomenal decrease in ionisation enthalpy from carbon to silicion.
Discuss the characteristics of group 14 elements in terms of:
(i) Oxidation states
(ii) Metallic character.
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