Final answer:
A functional group imparts characteristic properties to organic compounds and helps classify them into various classes. Examples include hydroxyl for alcohols and carbon-carbon multiple bonds. Systematic names are unique for each compound following IUPAC nomenclature rules.
Step-by-step explanation:
A functional group is a specific grouping of atoms within a molecule that is responsible for a characteristic set of reactions and properties.
The concept of functional groups is central to organic chemistry because it helps in classifying organic compounds into different classes.
Each class consists of a series of compounds that contain a common functional group, such as alcohols, aldehydes, and ketones.
An example to illustrate this concept would be the hydroxyl group (-OH), which is the functional group that defines alcohols. The presence of a hydroxyl group within a molecule greatly influences its chemical behavior, making alcohols distinct from hydrocarbons which do not possess this group.
Therefore, understanding functional groups helps in predicting the behavior and reactivity of organic compounds.
It is important to note that a carbon-carbon multiple bond is indeed considered a functional group because it distinctly affects the molecule's chemistry, just like single atoms or groups of atoms would.
On the other hand, while two substances cannot have the exact same systematic name and be different compounds, as systematic nomenclature is designed to uniquely identify a chemical substance, related compounds can have very similar systematic names that reflect their structural differences.
This systematic naming is governed by rules set by the IUPAC (International Union of Pure and Applied Chemistry).