11. As there are always equal numbers of irreducible representations and classes of symmetry operations , the tables are square. 12. Any symmetry operation in a molecule's point group acting on the molecule itself will leave it unchanged. 13. These elements can be a point, line or plane with respect to which the symmetry operation is carried out. 14. The symmetry operation is an action, such as a rotation around an axis or a reflection through a mirror plane. 15. It only has two symmetry operations : identity ( E ) and a mirror plane that goes through the three atoms. 16. In physics, groups are used to represent symmetry operations , and the usage of group theory could simplify differential equations. 17. This figure has four symmetry operations : the identity operation, one twofold axis of rotation, and two nonequivalent mirror planes. 18. In other words, a point group is a group that summarizes all symmetry operations that all molecules in that category have. 19. I'm trying to find out what symmetry operation ( not an inversion ) operates about a point in 3 dimensional space. 20. This is not an inversion in the sense used for symmetry operations of rigid molecules, since NH 3 has no inversion center.
