Applying our chirality criterion to a molecule we have to take into account conformational mobility: From most molecules, even highly symmetric ones, by rotation about single bonds conformations of low or no symmetry are easily constructed. For a chirality test the conformation of highest symmetry that is energetically accessible should be used.

For example, the staggered conformation of ethane (point group D_3d) is of course achiral, as is the eclipsed one (D_3h), whereas all intermediate conformations are in point group D₃, i.e. contain a C₃ and three C₂ only and thus are chiral. Ethane of course is an achiral compound.

eclipsed, D3h achiral	staggered, D3d achiral	intermediate, D3 chiral