Hydrocarbons are organic compounds consisting solely of carbon and hydrogen atoms, and they can be categorized based on the types of bonds between the carbon atoms. The primary classifications include alkanes, alkenes, and alkynes, which correspond to single, double, and triple bonds, respectively. This nomenclature is essential for clarity, as double bonds can occur between various atoms, but when specifically referring to carbon-carbon double bonds, the term "alkene" is used.

Understanding carbon structures is crucial for grasping more complex functional groups in organic chemistry. A key concept is the use of the "R group," which symbolizes a portion of the molecule that is being focused on, while the rest of the structure is represented generically. This allows chemists to simplify discussions about large molecules by indicating that the R group can represent a carbon chain of any length.

Additionally, when an alkane is part of a larger carbon chain, it is referred to as an "alkyl" group, denoted by the suffix "-yl." For example, in a six-carbon chain with a one-carbon branch, the main chain is identified as the alkane, while the branch is termed the alkyl. This distinction is important for understanding the structure and naming conventions in organic chemistry.