Nucleophilic substitution: A chemical reaction in which an electron-rich nucleophile selectively bonds with or attacks the positive or partially positive charge of an atom or a group of atoms to replace a leaving group; central to understanding Walden inversion.
Chiral center: An atom within a molecule that has four different groups attached to it, creating two non-superimposable mirror images known as enantiomers; crucial for the existence of Walden inversion.
Enantiomers:Molecules that are mirror images of each other but cannot be superimposed, much like left and right hands; produced through processes such as Walden inversion