# Organic Chemistry

## Overview

### Description

Organic chemistry is the study of molecules that contain carbon, with at least one carbon-hydrogen bond. Since carbon atoms can form up to four covalent bonds, there is a huge variety and number of organic molecules. Molecules that contain only carbon and hydrogen are called hydrocarbons, and many organic compounds have large hydrocarbon chains or ring structures. Because carbon-carbon bonds are nonpolar, organic molecules with large hydrocarbon components are hydrophobic. Hydrocarbons can also form bonds to a variety of functional groups that can change the physical properties of the hydrocarbon, such as the boiling point and solubility in water. Molecules that share functional groups also tend to have similar physical properties.

### At A Glance

• Organic chemistry is the study of carbon-based molecules that contain at least one carbon-hydrogen (${\rm{C{-}H}}$) bond.
• Alkanes are saturated hydrocarbons that contain only single carbon-carbon (${\rm{C}{-}{C}}$) and carbon-hydrogen (${\rm{C}{-}{H}}$) bonds.
• Alkenes are hydrocarbons with at least one carbon-carbon double bond (${\rm{C}{=}{C}}$). Alkynes are hydrocarbons with at least one carbon-carbon triple (${\rm{C}{\equiv}{C}}$) bond.
• Benzene is a hydrocarbon that is a 6-membered ring and is aromatic, giving it and its derivatives special properties.
• Alcohols, which are chain molecules, and phenols, which are ring molecules, both contain the hydroxyl (${{-}\rm{OH}}$) functional group attached to their parent carbon base. Ethers are two alkyl groups bridged by an oxygen atom (${\rm{R}{-}{O}{-}{R}^\prime}$), and thiols (mercaptans, ${\rm{R}-{SH}}$) contain the sulfhydryl (${{-}\rm{SH}}$) functional group.
• Aldehydes (RCHO) and ketones (RCOR′) contain a carbonyl fragment (${\rm{C}{=}{O}}$). Carboxylic acids (RCOOH) and esters (RCOOR′) also contain carbonyl groups but have an additional oxygen atom bonded to the carbonyl fragment.
• Amines (NRR′R″) and amides (RCONRR′) are ammonia derivatives in which hydrocarbon fragments are bound to a central nitrogen atom. Amines contain between one to three ${\rm{C}{-}{N}}$ single bonds, while amides contain one nitrogen atom bound to a carbonyl group and between zero to two additional ${\rm{C}{-}{N}}$ bonds.
• Chiral molecules have no plane of symmetry and their molecular mirror images are not related by rotation. These enantiomers have mirror images that are not superimposable on themselves.