CHEM 132C Study Guide - Spring 2018, Comprehensive Midterm Notes - Order Of Australia, Page 3, Symmetry Operation

• School: UC-Irvine
• Department: Chemistry
• Course: CHEM 132C
• Professor: Murray

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.