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

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

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.

3 4

Trigonal planartetrahedral

Exceptions to the "Octet Rule"

. Consider BF3 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.