Final answer:
Saturated hydrocarbons, such as alkanes, have only single bonds and contain the maximum number of hydrogen atoms. Unsaturated hydrocarbons have double or triple bonds and fewer hydrogen atoms. Saturated hydrocarbons undergo substitution reactions, while unsaturated ones are more reactive and participate in addition reactions.
Step-by-step explanation:
The difference between saturated and unsaturated hydrocarbons lies in the type of bonds between the carbon atoms. Saturated hydrocarbons, such as alkanes, have single bonds only and are 'saturated' with hydrogen atoms. This means they contain the maximum number of hydrogen atoms possible for that number of carbon atoms. On the other hand, unsaturated hydrocarbons include alkenes and alkynes, which have at least one double or triple bond, respectively, between carbon atoms. These compounds are not 'saturated' with hydrogen atoms as they have fewer hydrogen atoms than the maximum possible due to the presence of multiple bonds.
When discussing the reactions characteristic of these hydrocarbons, saturated hydrocarbons tend to undergo substitution reactions, where atoms or groups of atoms are replaced without changing the hydrocarbon backbone. Meanwhile, unsaturated hydrocarbons are more reactive and typically undergo addition reactions, where atoms or groups of atoms are added to the multiple bonds, effectively 'saturating' the molecule with additional atoms.
In terms of isomers, the different bonding in saturated and unsaturated hydrocarbons gives rise to various isomeric forms. Structural isomers have the same molecular formula but differ in the connectivity of atoms. Geometric isomers, which are a type of stereoisomer, occur in unsaturated hydrocarbons due to the restricted rotation around the double bond. This leads to molecules that have the same formula but differ in the orientation of groups around the double bond.