Short Answer Type
Long Answer TypeWhat are silicates? Discuss briefly their structures.
Silicate is the general name given to a group of minerals which have silicon - oxygen bonds. Rocks, soils and clays consist of almost entirely silicate minerals such as quartz, mica, asbestos, feldspars and zeolites.
(i) Quartz is a crystalline form of silica (SiO2).
(ii) Mica is a potassium aluminium silicate KAl3Si3O10(OH)2.
(iii) Feldspar is a potassium silicate KAlSi3O8.
(iv) Asbestos is a calcium magnesium silicate CaMgSi2O6.
Structure: All silicates involve silicon-oxygen single bonds. These may either Si - O bonds or Si - O - bonds. The basic structural unit of all silicates is the 
In this ion, silicon is sp3 hybridised. Each sp3 hybridised orbital of silicon combines with an orbital of the oxygen atom to form silicate ion which is tetrahedral in structure. 
Such tetrahedral units 
are linked together in different ways to give chains, rings, sheets and three-dimensional networks.
Short Answer TypeFor a compound LiAl(SiO3)2, what is the charge on SiO3 unit? What is the arrangement of oxygen atoms around the silicon atom?
Long Answer TypeShort Answer TypeLong Answer TypeExplain the difference in properties of diamond and graphite on the basis of their structures.
Short Answer TypeExplain why is there a phenomenal decrease is ionisation enthalpy from carbon to silicon.
Switch
. How will they behave with water? Justify
