CHEM 107 Chapter 4: Lec 01 SYMMETRY ELEMENTS & OPERATIONS (Ch. 4- book notes).pdf
Document Summary
Symmetry elements: mirror planes, axis of rotation, inversion. 1: to contain a given symmetry element, a molecule must have exactly the same appearance after the operations as before. (indistinguishable) Identity operation (e): causes no change in the molecule: is characteristic of every molecule, even if it has no symmetry. Rotation operation (cn): aka: proper rotation: rotation through 360 /n about a rotation axis. 2: we use counter-clockwise rotation as a positive rotation. Highest order rotation axis (principle axis): the cn axis having the largest value of n in a molecule with more than one rotation axis. Horizontal reflection operation ( ): when plane is to the principle axis of rotation. Vertical reflection operation ( / ): contains the principle axis of rotation. Inversion (i): each point moves through the center of the molecule to a position opposite the original position and as far from the center point as where it started. (x, y, z -x, -y, -z)
