What does the molecular formula R-NH2 signify?

The molecular formula R-NH2 represents an amine, which is characterized by the presence of a nitrogen atom attached to two hydrogen atoms and a carbon-containing group (R). Amines are derived from ammonia (NH3) and can be thought of as ammonia with one or more hydrogen atoms replaced by organic groups.

The R group, which can be any hydrocarbon chain or aromatic ring, indicates the presence of organic characterization. When nitrogen is bonded in this way, it typically gives rise to basic properties, allowing the amine to act as a nucleophile in many biochemical reactions. The presence of the -NH2 group is a defining feature of primary amines, highlighting its role in biochemistry, particularly in the formation of amino acids and other biologically relevant compounds.

In contrast, a hydroxyl group refers to the functional group -OH, which is part of alcohol molecules, whereas a ketone contains a carbonyl group (C=O) located within a carbon chain. Understanding these definitions and distinguishing features helps clarify the functionality and reactivity of different organic compounds in biochemical contexts.