REEL lab #1 will start on Wed/Thurs of this week. Your TA will hand out the lab discussion and procedure to you today or tomorrow and you will definitely need to read it and do the homework problems before you come to lab. The quiz this week will be solely based on the content of REEL Lab #1, which is d to d transitions and color of transition metal complexes.
In class today I reviewed some concepts from general chemistry about electrons and orbitals and then gave a very brief background on Valence Bond Theory and Crystal Field Theory (CFT). In our class we will be taking Crystal Field Theory and covering it in a little more depth than the book does. We need to do this in order to understand charge transfer excitations, which are the primary excitations responsible for color in pigments such as PbCrO4.
This led us into the discussion of Molecular Orbital Theory, which depends primarily on the symmetry (or shape) of the atomic orbitals interacting, as well as their energy. Remember that when molecules form, they are trying to lower the overall energy of the entire molecule. They do this by stabilizing the electrons as much as possible.
Remember that the more stable something is, the LOWER the energy.
A stronger bond becomes more stable in energy, this lowers its overall energy.
The better the orbital overlap, the stronger the bond, the more stable (lower energy) the bonding molecular orbitals. This also makes the anti-bonding orbitals very destabilized (higher in energy).
We then went through the details of the molecular orbital diagram for an H2 molecule and discussed the similarities and differences to an O2 molecule. We then transitioned into the MO diagram of Cr(H2O)63+. This molecular orbital diagram is listed in the discussion of REEL Lab #1, so be sure to look it over before class on Wed.
I know we have been jumping around a bit, but here is what you need to be keeping up with:
Read REEL Lab #1
You should have the first Transition Metal homework set complete
You should have the Transition Metals: Color and Orbital Overlap assignment complete before you go to lab this week.
Read Chem 123 REEL Orbitals, Bonding, MO Diagrams, and Color, which is posted on carmen.
If you have any questions please let me know. See you in class on Wed, Dr. Fus
P.S. Congrats to Mark Titus and Club Trillion for reaching 1,000,000 hits :)
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