Weekly Blog 10/7 through 10/13

This week was a very busy week. We started it off with learning about vsepr models and how molecules are shaped by the bonded and non-bonded pairs of electrons. The vsepr models demonstrated why water has an irregular shape and why other atoms have their shapes. It also taught us how you can figure out the shape of the molecule knowing only the mount of bonded and unbonded pairs of electrons and the number of atoms around the central one. Here is a diagram of some vsepr structures.

We also learned about formal charges, which are used in Lewis dot diagrams in order to denote the charges of atoms. The formal charges are a result of polarity in a molecule, where one atom has more pull on the shared electron than the other. This can affect the vsepr structure of the molecule because of the way bonds are formed when an atom is polar. A molecule can be non-polar even if some of the bonds are polar. If the dipole moments all add to zero, then the molecule will have a net dipole moment of zero and will be non-polar. Here is a picture of a molecule and it's dipole moments.

At first I didn't understand polarity and dipole moments at all, but after I watched the lectures several times it began to make more sense. I have a much better understanding now than I did when I first watched the lecture. I still think that I need a lot more practice with it, however. Also, whiteboarding the Lewis structures and figuring out the molecular and electron domains was extremely helpful and I now know what I'm doing with those. Overall, my understanding of the material is good, but it can definitely be better.