Silicon is the second most abundant element (~27.2%)in the earth's after oxygen (45.5 %) Carbon. Silicon, germanium, tin and lead constitute the group 14 of the periodic table. Chemistry of silicon is distinctly different from that of carbon. For example, under standard conditions CO_(2) is a gas whereas SiO_(2) is a covalent solid. The reactivities of C Cl_(4) and SiCl_(4) are different. For example SiCl_(4) can be easily hydrolysed and is prone to substitution reactions, whereas C Cl_(4) is inert. The observed difference is because (a)carbon atom has smaller size than hence substitution is not possible (b)carbon is more electronegative than silicon ( c)silicon has low lying unoccupied orbitals (d)C-Cl bond is stronger than Si-Cl bond Silicon has high affinity for oxygen to form silicates having SiO_(4)^(4-) units.Silicates can have chain or cyclic structures.