This chapter begins with the study of the simplest organic molecules: hydrocarbons. Of the hydrocarbons, the most basic molecules are alkanes, which consist of only single bonds. Alkanes may be unbranched, branched, or cyclic. In addition to our examination of Alkanes, we will also take a brief look at alkenes and alkynes, which contain double and triple bonds. These molecules can be named using the IUPAC nomenclature system, which systematically and unambiguously identifies any molecule. Because organic chemists tend to draw lots of large molecular structures, several shorthand notations are frequently used, including condensed structures, line-angle drawings and abbreviations for constituent groups.
We also introduce the extremely prevalent concept of isomerism: different molecules with the same molecular formula. There are two types of isomers. Constitutional isomers differ in the connectivity of bonds, whereas stereoisomers have the same bond connectivities but have bonds oriented differently. Stereoisomerism is exhibited by alkenes due to the rigidity of pi-bonds, but we'll see in the next chapter that stereoisomerism is a much more general phenomenon that occurs in a wide variety of compounds.