Conformational analysis is the study of molecular conformations (see molecule), i.e., the spatial arrangements of the atoms that can be interconverted by rotation about single bonds (see chemical bond). In general, different conformations are transient and nonisolable, unlike different configurations (see stereoisomers). But if large substituents, such as bromine and phenyl groups, are attached to adjacent atoms, steric hindrance or interference may cause the eclipsed conformation to be less stable than the staggered. This may affect reaction rates. Conformational affects are most important in alicyclic compounds.