Operation identity E leaves the molecule unaffected. We imagine a onefold rotational axis C_{1}, i.e., one complete turn about 360° is needed to make the molecule fit the with the original. Of course, all molecules, asymmetric as they may be, possess a "symmetry" of this kind. Although such an operation seems of no use, it plays a role comparable to the one of number zero in addition and of one in multiplication. In all groups of symmetry operations, E is the neutral element.
Examples



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