Memorandum

To:       CHM 1045 Recitation Instructors
          Dillhyon, Martin, Callihan, Guile

From:     Robley Light

Date:     March 25, 1996

Re:       Recitation 11, week of March 25


     Hand back quizzes and go over them.

Leftover material from Chapter 8:

     Calculating oxidation numbers.

Chapter 9--most of the chapter.

Geometry of molecules determined from:

     Electron pair geometry (epg) based on number of electrons
     about central atom.

     Molecular pair geometry, which varies from epg when there is
     one or more lone pair of electrons.

     Orbital hybridization associated with each epg.

     (Most of this is summarized in tables 9.2, 9.3, and 9.5)

Polarity of molecules (presence or absence of a dipole moment)
determined from molecular geometry, with vector addition of
individual bond dipoles.  (Symmetrical structures are non polar
even if bonds in the molecule are polar).

Valence bond theory--formation of bonds by overlap of atomic
orbitals:

     sigma bonds (s-s, s-p, and p-p)

     pi bonds (p-p overlapping sideways)