The stereochemistry of radical halogenation depends on whether the reacting molecule is chiral or achiral. For example, achiral n-butane, upon radical chlorination, gives 1- and 2-chlorobutane. The reaction introduces a new chiral center, as one of the products is a racemic mixture. The formation of a racemic mixture is driven by the generation of an achiral trigonal planar radical intermediate, on which chlorine can attack from either face, yielding equal amounts of R and S enantiomers. This makes carbon-2 hydrogens enantiotopic in nature. Similarly, radical halogenation at an existing chiral center also forms a racemic mixture. Here, the radical intermediate loses the reactant's configuration and becomes achiral, enabling the halogen attack from either side and producing equal amounts of enantiomers. In contrast, a chiral compound with a chiral carbon not involved in radical halogenation gives diastereomeric products, introducing a second chiral center. The existing chiral center makes the trigonal planar radical intermediate chiral. Consequently, chlorine attacks to a greater extent at one face than the other and produces chiral, diastereomeric products of unequal amounts.