This chapter focuses on a class of isomers that differ only in the spatial arrangement of attached atoms and groups about an atom. Enantiomers are different molecules, and each requires a unique name. A set of standardized rules of nomenclature have been developed that distinguish two enantiomers based on the relative position of atoms or groups. A chiral compound that is not enantiopure is a mixture of both enantiomers. Electromagnetic radiation travels as a transverse wave that consists of electric and magnetic fields that oscillate perpendicular to one another. A transverse wave oscillates perpendicular to the direction of the wave's advance. Stereogenic carbons are found in cyclic molecules but monosubstituted cycloalkanes are not chiral.