R(-) or S(+) Forms

R(-) and S(+) refer to specific orientations of molecules known as enantiomers, which are mirror images of each other. These molecules are like left and right hands—they have the same parts but in different arrangements. The R(-) form rotates plane-polarized light to the left (counterclockwise), while the S(+) form rotates it to the right (clockwise). This distinction is important in chemistry and pharmacology because different enantiomers can have different effects in biological systems. The R/S notation helps scientists identify and describe the three-dimensional configuration of chiral molecules.