What is Organic Chemistry?

Carbon forms the backbone of organic compounds because it can form four strong bonds with other carbon atoms and elements like hydrogen, oxygen, nitrogen, and sulfur. This versatility allows carbon to create diverse structures including ring-shaped, branched, and straight-chain arrangements. Carbon's bonding flexibility enables the formation of the vast variety of organic molecules found in nature and synthesized by chemists.

Hydrocarbons contain only carbon and hydrogen atoms, while functionalized hydrocarbons have one or more hydrogen atoms substituted by functional groups. Functional groups are characteristic atoms or groups of atoms that determine the properties of hydrocarbon derivatives. For example, alcohols contain an –OH functional group, and carboxylic acids contain a carboxyl functional group, each conferring distinct chemical and physical properties.

The three main types of hydrocarbons are alkanes, alkenes, and alkynes. Alkanes contain only single bonds between carbon atoms. Alkenes contain one or more double bonds, while alkynes contain one or more triple bonds. These different bonding arrangements result in distinct molecular structures and chemical properties within each hydrocarbon family.

Compounds with the same functional group share similar properties because the functional group is the characteristic atom or group of atoms that primarily determines the compound's chemical and physical behavior. All organic compounds carrying a common functional group fall under the same family and exhibit similar reactivity and properties. This relationship allows chemists to predict compound behavior based on functional group identity.

Understanding organic compound structure is critical for developing plastics, soaps, perfumes, sweeteners, fabrics, pharmaceuticals, and many other substances used daily. Organic compounds form fundamental building blocks of life like DNA and plant cell walls, as well as energy-liberating materials like fuels. Knowledge of their structures and reactions enables chemists to design compounds with specific functions for practical applications.

The general formula R-OH uses the letter R to designate the hydrocarbon portion of a molecule, followed by the specific functional group. For alcohols, the –OH group is bonded to the hydrocarbon portion. This notation system allows chemists to represent entire families of compounds concisely and to predict their properties based on the functional group present, regardless of the specific hydrocarbon structure.

Some carbon-containing compounds like carbonates, cyanides, and simple oxides (CO and CO2) are not typically classified as organic compounds because they lack the characteristic properties and structural diversity of organic molecules. Organic compounds are defined by their composition of carbon bonded to hydrogen, oxygen, nitrogen, or sulfur, and their ability to form complex structures. These exceptions represent a distinct category of inorganic carbon compounds.