1. Review Topics we have covered: inverse square law Electrostatics Charges Polarity non-polar covalent bonds polar covalent bonds ionic bonds dipole-dipole forces london dispersion forces coulomb’s law protein folding Lewis structures VSPER and molecular geometry

2. http://workbench.concord.org/database/activities/157.html - overview http://workbench.concord.org/database/activities/213.html http://www.physicsclassroom.com/Class/estatics/U8L3b.cfm http://mw2.concord.org/public/part2/bondtype/page1.cml http://workbench.concord.org/database/activities/235.html Some web addresses we have used….. Since our last review: http://www.chem.purdue.edu/gchelp/vsepr/example32.html Concord workbench activities: 302 molecular geometry 225 protein folding and 227 intermolecular attractions

3. Review Questions 1. For A and B above: a)How many regions of electron density does each have? b)What is the molecular (electron) geometry for each? 2. Consider NH 3 and BF 3 for each of these complete the following: a)The lewis dot structure for each. b)Will these two molecules have the same electron geometry? Explain why or why not. In your explanation include what kind of geometry each has. 34 Trigonal planar tetrahedral

4. Exceptions to the "Octet Rule". Consider BF 3 as well.. The presence of lone pair electrons on each F atom potentially allows additional bonding interactions. Here are some images and info to help with question 2 The structure of NH 3 Structure and info on BF 3 … in the pale blue below you can see acceptable lewis structures… the major goal is for you to see there is no lone pair in this molecule. My writing is in yellow boxes Activity 302 on the concord workbench may also help.