Here's why:
* Saturated hydrocarbons have only single bonds between carbon atoms. Each carbon atom is bonded to the maximum number of hydrogen atoms possible, making the molecule "saturated" with hydrogen.
* Unsaturated hydrocarbons have at least one double or triple bond between carbon atoms. This means there are fewer hydrogen atoms attached to the carbon atoms than in a saturated hydrocarbon with the same number of carbon atoms.
Examples:
* Ethane (C2H6) is a saturated hydrocarbon with a single bond between the two carbon atoms.
* Ethene (C2H4) is an unsaturated hydrocarbon with a double bond between the two carbon atoms.
* Ethyne (C2H2) is an unsaturated hydrocarbon with a triple bond between the two carbon atoms.
The presence of double or triple bonds allows unsaturated hydrocarbons to undergo addition reactions, where atoms are added to the molecule across the double or triple bond. This property makes unsaturated hydrocarbons more reactive than saturated hydrocarbons.
