symmetry elements .Symmetry operations are carried out with respect to points,lines,or planes called symmetry elements. Example: (a)An NH2 molecule has a (b)an H2O molecule has a threefold(C3)axis twofold (C2)axis. NH,has higher rotation symmetry than H,O(b) an H2O molecule has a twofold (C2) axis. (a) An NH3 molecule has a threefold (C3) axis NH 3 has higher rotation symmetry than H2O Example: •Symmetry operations are carried out with respect to points, lines, or planes called symmetry elements. symmetry elements