AP BIOLOGY

Detailed explanation-1: -The hydrocarbons that contain at least one double bond between two adjacent carbon atoms are called alkenes or olefins. The simplest alkene is ethylene (or ethene), given by the chemical formula C2H4.

Detailed explanation-2: -Like alkanes, alkenes are another homologous series of hydrocarbons. Alkenes are unsaturated hydrocarbons with one or more carbon-carbon double bonds. This C=C double bond is the functional group that defines a molecule as an alkene.

Detailed explanation-3: -There are three types of unsaturated hydrocarbons: alkenes, alkynes and aromatic hydrocarbons. Alkenes have one or more carbon-carbon double bond. Alkynes have one or more carbon-carbon triple bond, and aromatic hydrocarbons have a benzene or aromatic ring in their structure.

Detailed explanation-4: -Endocyclic double bonds have both carbons in the ring and exocyclic double bonds have only one carbon as part of the ring. Cyclopentene is an example of an endocyclic double bond. Methylenecylopentane is an example of an exocyclic double bond.

Detailed explanation-5: -Therefore alkenes are called unsaturated hydrocarbons owing to the presence of carbon-carbon double bond in alkene molecules, giving them characteristic addition reactions.