<Ol> <Li> Saturated hydrocarbons are the simplest of the hydrocarbon species . They are composed entirely of single bonds and are saturated with hydrogen . The formula for acyclic saturated hydrocarbons (i.e., alkanes) is C H. The most general form of saturated hydrocarbons is C H, where r is the number of rings . Those with exactly one ring are the cycloalkanes . Saturated hydrocarbons are the basis of petroleum fuels and are found as either linear or branched species . Substitution reaction is their characteristics property (like chlorination reaction to form chloroform). Hydrocarbons with the same molecular formula but different structural formulae are called structural isomers . As given in the example of 3 - methylhexane and its higher homologues, branched hydrocarbons can be chiral . Chiral saturated hydrocarbons constitute the side chains of biomolecules such as chlorophyll and tocopherol . </Li> <Li> Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms . Those with double bond are called alkenes . Those with one double bond have the formula C H (assuming non-cyclic structures). Those containing triple bonds are called alkyne . Those with one triple bond have the formula C H . </Li> <Li> Aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring . </Li> </Ol> <Li> Saturated hydrocarbons are the simplest of the hydrocarbon species . They are composed entirely of single bonds and are saturated with hydrogen . The formula for acyclic saturated hydrocarbons (i.e., alkanes) is C H. The most general form of saturated hydrocarbons is C H, where r is the number of rings . Those with exactly one ring are the cycloalkanes . Saturated hydrocarbons are the basis of petroleum fuels and are found as either linear or branched species . Substitution reaction is their characteristics property (like chlorination reaction to form chloroform). Hydrocarbons with the same molecular formula but different structural formulae are called structural isomers . As given in the example of 3 - methylhexane and its higher homologues, branched hydrocarbons can be chiral . Chiral saturated hydrocarbons constitute the side chains of biomolecules such as chlorophyll and tocopherol . </Li> <Li> Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms . Those with double bond are called alkenes . Those with one double bond have the formula C H (assuming non-cyclic structures). Those containing triple bonds are called alkyne . Those with one triple bond have the formula C H . </Li> <Li> Aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring . </Li>

A hydrocarbon with a double bond is an