1. Covalent Compounds

2. Resonance Resonance structures are those that occur when it is possible to draw two or more valid electron dot structures that have the same number of electron pairs for a molecule or ion. Not all molecules will have resonance If they do, their actual bonding will be a hybrid of all resonance structures

3. Processing Time… Draw a valid Lewis structure for ozone, O 3

4. Processing Time…

5. Exceptions to the Octet Rule What’s the octet rule? What does the word exception mean? The octet rule cannot be satisfied in molecules whose total number of valence electrons is an odd number. Some will have fewer than eight, some will have more than eight!

6. How do you know you have an exception? If there will be more than 4 bonds around the central atom Ex: PCl 5 and SF 6 Also, when you have left over electrons and everyone else has an octet, you can put the extra electrons on the central atom Ex: SF 4

7. VSEPR Theory Valence Shell Electron Pair Repulsion Theory – Helps us tell the shape of the molecule – Determined by the bonds that hold the molecule together – Also referred to as the molecule geometry of the molecule

8. VSEPR Theory The repulsion between electron pairs causes molecular shapes to adjust so that the valence-electron pairs stay as far apart as possible. – Why would electron pairs repel each other? – Why would they push each other as far apart as possible?

9. Steps to find the molecular geometry 1.Draw the Lewis structure for the molecule (remember, some may have more than one but all you need is one valid structure) 2.Count the bonding and nonbonding sites around the central atom 3.Use your VSEPR chart