Compounds that are non-superimpossible mirror images (mirror images that can not be overlayed in any conformation) are called enantiomers. Compounds that have enantiomers are called chiral molecules. Why do we care? Things that are chiral: DNA Proteins Amino acids thus biology in general thus humans are chiral Many complex organic molecules are chiral (like medicines) Each enantiomer of a chiral molecule reactive differently with other chiral molecules or chiral enviroments. The most simple chiral molecules One stereocenter tetrahedral carbon (or other atom) with four different substituents: two ways to arrange.