What is the primary function of a functional group in organic compounds?

The primary function of a functional group in organic compounds is to determine the chemical reactivity and properties of the molecule. Functional groups are specific clusters of atoms within molecules that are responsible for the characteristic reactions of those molecules. They dictate how the molecule interacts with other substances, which can lead to various chemical reactions. For instance, the presence of a hydroxyl group (-OH) classifies a compound as an alcohol, which influences its solubility and reactivity compared to other compounds. This chemical specificity is crucial in organic chemistry, as different functional groups confer different properties, thereby affecting the overall behavior of the compound in chemical reactions.

While boiling point and stabilization can be influenced by functional groups as well, these are secondary effects resulting from the properties and reactivity associated with the functional groups themselves. Similarly, molecular weight is determined by the overall composition of the compound, not specifically by its functional groups. Hence, the defining characteristic of functional groups is their role in determining how organic molecules react and behave chemically.