CHEM 132C Study Guide - Comprehensive Final Exam Guide - Order Of Australia, Page 3, Symmetry Operation
Document Summary
Symmetry arguments used to make immediate assessments of properties of molecules. Molecules can be classified into groups according to their symmetry elements. Symmetry operation: action that leaves an object looking the same after it has been carried out. Rotation (symmetry operation) carried out around an axis (symmetry element) n-fold rotation about an n fold axis of symmetry (cn) D if (cid:448)erti(cid:272)al (cid:373)irror pla(cid:374)e (cid:271)ise(cid:272)ts the a(cid:374)gle (cid:271)et(cid:449)ee(cid:374) to c(cid:1006) a(cid:454)is. Inversion through center of symmetry (i) n-fold improper rotation about n-fold axis of improper rotation axis (sn) First, rotation through 360 degrees/n, then reflection through plane perpendicular to axis of that rotation. Point groups: classification of objects according to symmetry elements corresponding to operations that leave at least one common point unchanged. Space groups: symmetries arising from translation through space. No charge distribution if molecule is group cn. Only molecules belonging to cn, cnv, and cs may have permanent dipole moment.
