आल्केन
Alkanes occur widely in nature in different forms.These are the simplest hydrocarbons.The lower members(C1 to C4) are major constituents of the natural gas which is used as fuel in cooking, automobiles and in power generation plants.Some of the higher hydrocarbons(C6 to C8) are constituents of gasoline or petrol.Diesel contains different alkens C15 to C18. Waxe,that occur in nature as coating on green leaves contain C29 to C31 alkanes. Some alkanes possess exceptional biological activity. Undecane(C11 alkane) secreted by cockroach helps to attract opposite gender of its species. Cyclohexane, a cyclic alkane is one of the common component of mangoes. It is intended to study some interesting aspects of chemistry of alkanes in this chapter.
Alkanes="The saaturated aliphatic hydrocarbons are called as alkanes.
Alkane are open chain hydrocarbons in which all the four valencies of carbon are satisfied by four atoms or groups of atoms.These atoms are joined to carbon atom by sinle covalent bonds.Alkanes are also called as paraffins easily(Latin param means little and affin aeans affinty or reactivity).Some common alkanes and their molecular fomulae are mentioned below.
                        Methane      CH4
                        Ethane       C2H6
                        Propane      C3H8
                        Butane       C4H10
                        Pentane      C5H12
Thus all alkanes can be represented by the general formula CnH2n+2 where 'n' is an integer and indicates tha number of carbon atoms in the molecule.