Groups

The concept of a group is introduced using the example of the symmetry group of the ammonia molecule. In spite of its tiny size this molecule has a structural symmetry which is the same as the symmetry of a macroscopic trigonal pyramid. From the mathematical point of view, a group is an elementary structure, which proves to be a powerful tool for describing molecular properties. Three ways of dividing (and conquering) groups are shown: Subgroupsubgroups, cosets, and Classclasses. Spatial isometriesIsometries are introduced and an overview of molecular symmetry groupsMolecular symmetry group is given. The relationship between rotational groups and chiralityChirality is explained, and symmetry lowerings due to applied magnetic and electric fieldsElectricfield (E) are determined.