ABSTRACT

The chemicals of life are organic compounds, or compounds that contain carbon. Carbon is one of the few tetravalent atoms, meaning that it has four valence electrons available to form bonds with other atoms. The valence of the key elements forms the basis of the structural model of organic chemistry that permits people to predict which combinations of atoms will combine to form stable molecules. The structural and functional makeup of a cell results from combinations of four basic molecular types, each of which falls into one or more of the categories. Many organic compounds are not identical to their mirror images. These molecules are called chiral, from the Greek cheir, since human hands are also mirror images of each other but not superposable. Chirality is of great importance in chemistry and biology for several reasons. Molecular orbital calculations become highly complex for molecules more sophisticated than hydrogen.