Basic idea of what are organic compounds. Why carbon is used in case of organic chemistry? Classification of organic compounds based on e arrangement of carbon atoms, that is if they are in a linear chain or in a branch chain and how many bonds are present between the carbon atoms like alkanes, alkenes and alkynes. Another classification is there based on the presence of different types of functional groups like alcohols, carbonyl compounds, carboxylic acids, cyanides, amines, nitro compounds, etc.