In Lesson 1 you studied alkanes and alkyl halides in which carbon atoms bonded to other carbon atoms along with hydrogen and halogen atoms using single bonds. From your work in the Bonding section of this lesson you know that the carbon atoms were using sp3 hybridization and sigma bonds to make those compounds.
Carbon compounds, of course, are not restricted to having single bonds using sp3 hybridization. Part of the nature of carbon is that it can form double bonds to other carbon atoms using sp2 hybridization. When a carbon-to-carbon double bond is present in a molecule, it is an alkene rather than an alkane. Because the -ane ending indicates that only single bonds are present in the molecule we must modify the ending on the name. When a double bond is present in the molecule, we use the ending -ene. You will learn more about naming alkenes in the Nomenclature pages of this section.
Along with nomencalture, you will learn about the structural features, properties and reactions of alkenes.
Incidentally, organic molecules which contain double bonds are referred to as being unsaturated molecules. For that matter, molecules which contain triple bonds are also referred to as being unsaturated. Those saturated and unsaturated, and even the polyunsaturated vegetable oils that you have heard of, are classified as such, depending on whether or not they have double bonds within their molecules.
Distance Learning questions
Clackamas Community College