Hydro Carbons

Hydro Carbons

Compounds made of carbon and hydrogen atoms only are celled hydrocarbons. The natural source of hydrocarbons is petroleum.

Hydrocarbons can be divided into various classes

Aliphatic Hydrocarbons :
The word aliphatic is derived from the Greek word aleiphar meaning fat. Aliphatic hydrocarbons were named so because they were derived from fats and oils. Hydrocarbons can be acyclic compounds, which are straight chain compounds, or cyclic compounds, which have rings of carbon atoms.

Aromatic Hydrocarbons :
The word aromatic is derived from the word aroma meaning fragrance. The aromatic compounds have a characteristic smell. Structurally, they include benzene and its derivative. The aliphatic hydrocarbons can be divided into two categories: saturated hydrocarbons and unsaturated hydrocarbons. In saturated hydrocarbons, carbon atoms are linked to each other by single bonds, whereas in unsaturated hydrocarbons, multiple bonds (double and triple bonds) are present between carbon atoms.

Classificaton of Hydrocarbons

Hydrocarbons are classified as :
(i) saturated hydrocarbons
(ii) unsaturated hydrocarbon
(iii) aromatic hydrocarbons

1. Saturated hydrocarbons

The hydrocarbons in which carbon atoms and singly bonded are called saturated hydrocarbons. Saturated hydrocarbons are also called alkanes or paraffins. Alkanes are relatively unreactive under ordinary laboratory conditions. So, alkanes are also called paraffins because paraffins means little reactive.

2. Unsaturated hydrocarbons

The hydrocarbons in which carbon atoms are either doubly or triply bonded are called unsaturated hydrocarbons. Doubly bonded (carbon carbon atoms) hydrocarbons are called alkenes. The general formula of alkene is C_nH_2n.

Triply bonded carbon
Carbon atoms containing hydrocarbons are called alkynes. The general formula of alkynes are C_nH_2n-2.

3. Aromatic hydrocarbons

These are homocyclic compounds which contain atleast one benzene ring in which carbon atoms are linked to one another by alternate single and double bonds. In Greek, aroma stands for sweet smell. Compounds in these classification have placement small. Hence, they are called aromatic compounds.

» Isomerism

Two or more compounds having same molecular formula but different physical and chemical properties are called isomers and this phenomenon is called isomerism

» Polymerisation

The simple molecules which combine to form a macro molecule is called polymer. The process by which the simple molecules (monomers) are converted polymer is called polymerisation.

Natural occurring polymers are protein, nucleic acid, cellulose, starch etc.