Mirror Planes of Symmetry If two groups are the same,carbon is achiral.(animation) A molecule with an internal mirror plane cannot be chiral.* Caution!If there is no plane of symmetry,molecule may be chiral or achiral.See if mirror image can be superimposed. internal mirror plane of symmetry (o) Mirror Planes of Symmetry ❖If two groups are the same, carbon is achiral. (animation) ❖A molecule with an internal mirror plane cannot be chiral.* Caution! If there is no plane of symmetry, molecule may be chiral or achiral. See if mirror image can be superimposed