These are the compounds which are composed of Hydrogen and Carbon. Each carbon atoms has four bonds. They can be saturated (single bond), unsaturated (double or triple bond), acyclic (without rings) and cyclic (with rings)

Hydrocarbons can be classified as

1.      Alkanes

2.      Alkenes

3.      Alkynes

4.      Aromatic Hydrocarbons

Alkanes (Paraffins): They contain single bonds. They are called saturated hydrocarbon. The first four are gases, next thirteen are gases and the higher are solids. Their general molecular formula is C_nH_2n+2.

Eg. Methane (CH₄), Ethane (C₂H₆), Propane (C₃H₈), Butane (C₄H₁₀), Pentane (C₅H₁₂) etc

Alkenes (Olefins): They contain at least one double bond. They are called unsaturated hydrocarbon. The first three are gases, next fourteen are liquids and higher are solids. Their general molecular formula is C_nH_2n.

Eg. Ethene (C₂H₄), Propene (C₃H₆), Butene (C₄H₈) etc

Alkynes: They contain one least one triple bond. They are called unsaturated hydrocarbon. The first three are gases, next eight are liquids and higher are solids. Their general molecular formula is C_nH_2n-2.

Eg. Ethyne (C₂H₂), Propyne (C₃H₄) etc

Aromatic Hydrocarbons (Arenes): They are planar, ring structures with alternating single and double bonds: Eg. Benzene (C₆ H₆), Toluene etc.

The Aromatic Hydrocarbons which contains benzene ring are called benzoids (cyclic) and the compounds which do not contain benzene rings are called non benzoids (acyclic).