Asymmetric Molecule. If all the four substituents attached to carbon are different, the resulting rnolecule will lack symmetry. Such a molecule is called asymmetric molecule. Asymmetry of molecule is responsible for optical activity in such organic compounds.
Chiral : An object which is non-super imposable on its mirror image is said to be chiral. 'The property of being chiral is known as chirality. A chiral object is also called disymmetric, e.g., right and left hands are non-super imposable as shown in figure.
Achiral. Achiral objects are those objects which are super imposable on their
Asymmetric Carbon : The carbon atom which is attached with four different groups of atoms is called asymmetric carbon. The molecule having asymmetric carbon atom is called disymmetric. When a molecule contains on'e asymmetric carbon, it is always chiraL Common examples are glyceraldehyde (2, 3-dihydroxypropanal), Lactic acid (2-hydroxypropanoic acid), bromochloroiodomethane, etc. These are asymmetric molecules.
It must be kept in mind that the condition for chirality is not only the presence
of asymmetric carbon atoms but also the asymmetry of the molecule as a whole.
Enantiomers : The stereoisomers which are non-superimposable mirror images are called enantiornen.