R and S nomenclature

In chemistry, R and S nomenclature describes the 3D arrangement of atoms around a chiral center (a carbon atom with four different groups attached). R (from Latin *rectus*) means the groups are arranged clockwise, while S (from Latin *sinister*) indicates a counterclockwise arrangement when viewed from a specific perspective. This system helps chemists distinguish between mirror-image molecules, known as enantiomers, which can have different biological effects. The assignment involves prioritizing groups by atomic number and then observing the order of these groups in space.