This week we had a lot going on in class. We worked with WebMO to create virtual representations of our molecular domain geometries so we could better visualize the shape of the atoms and build upon our knowledge of geometries that we did with the balloon and gum drop models. Basically we just built upon the main ideas that we had learned last week on VSEPR.

            For the first half of this week, we worked online building our models that we had already learned about from our balloon and gum drop lab. We created a molecular orbital to represent our molecule and we could use this orbital to find out a lot of information. We looked at the dipole moments that occurred in the molecule and the individual dipole bonds that were present. From this we could see the partial charges in atom and could even better understand the partial charges in the molecule by looking at the electrostatic potential map. Atoms in the molecule that were the most electronegative appeared red on the map and the atoms that were least electronegative appeared as a cool color, either blue or green. We could also see the bond angles that were present in the geometries even though we already knew this from the worksheets and lectures that we had done previously.

            We found out from this lab that the unpaired electrons on the central atom are electron clouds that push down on the bonds of the molecule and reduce their angles and this is why they sometimes deviate away from their standard value.

            We also talked a little bit about pi and sigma bonds this week. Pi bonds occur when there is an overlap of the p orbitals while sigma bonds occur when there is an overlap of the s orbitals or sp orbitals. This concept was a little complex at first to understand but made more sense to me when I understood that sigma bonds occur in all bonds while pi bonds occur in bond orders that are higher than one (i.e.: a double or triple bond). For a double bond there is one pi bond and one sigma bond while for a triple bond there are two pi bonds and one sigma bond.

            Lastly, we talked a little bit about hybridization or the combination of s and p orbitals. This is the mixing of orbitals to create new orbitals that are more suitable for bonding. Hybridization only occurs in the s and p orbitals. For two bonds in the molecule there is an sp hybridization, for three bonds it is sp², and for sp³ there are four bonds. You cannot go any further than this.

            I think that I had a good grasp on the material this week and my participation was there every day. My understanding is at about an 8 and I just need more practice with the material. Other than that everything is going well.

http://www.youtube.com/watch?v=vyT5YF4UEy0