Could you help me to solve this question: how many atomic orbitals are required to construct the molecular orbital for 1.CH3- ,C2H2(ACETYLENE), CH2O(FORMALDEHYDE) by using STO-3G basis set ?
@jorgehwb
8 жыл бұрын
Hi Professor, Thank you so much for your videos! They're incredibly, incredibly helpful. I was wondering, however, why the electrons in the 2s orbital for the 2p atoms are not included in your molecular orbital diagram. As they're in the same principal energy level, wouldn't they be considered valence and thus participate in bonding? Or does the fact that the 2s orbital is filled remove it from bonding consideration? Thank you!
@ChemSurvival
8 жыл бұрын
Hi Harry. Thanks for the great question! You are correct that the 2s subshell must be considered to get a complete energetic picture of the valence shell interactions in the atoms of diatomic molecules like these. In this video I have omitted them for clarity, since in all examples here (except the special case of sigma-pi mixing in nitrogen) the sigma and sigma star M.O.s that result from the 2s interactions are completely filled and lower in energy than those MOs created by interactions between and among the 2p orbitals. As you suggested, this means that the 2s MOs cancel one another out completely and therefore do not contribute to bonding interactions. wps.prenhall.com/wps/media/objects/3311/3391094/imag0908/AAAVJLK0.JPG wps.prenhall.com/wps/media/objects/3311/3391094/imag0908/AAAVJLN0.JPG Here are links to relevant images form Brown, LeMay and Bursten. I think you will see what I am getting at.
@jorgehwb
8 жыл бұрын
Thank you so much! I think I'm starting to get it now. One last question (if you don't mind)... what happens when one of the atoms in question bonds to multiple other atoms? Do the electrons in the * orbitals carry over into the next interaction?
@ChemSurvival
8 жыл бұрын
Harry Gray Hi Harry. Exactly. Molecular orbitals can span long distances across many, many atoms. If you are taking or plan to take Organic Chemistry, you will encounter some examples during that course, most notably in conjugated or aromatic compounds. Here is another video of mine that covers a simple example of these larger molecular orbitals. kzitem.info/news/bejne/02eCrJ-ZhH9noXY
@jorgehwb
8 жыл бұрын
Thank you!
@Thwapwhacket
8 жыл бұрын
Excellent video, except that you did not account for the lone pairs on the nitrogen atoms of the diatomic N2 molecule.
@ChemSurvival
8 жыл бұрын
I assume that you are referring to the 2s sigma and 2s sigma star M.O.s You are correct that I omitted them, since they do not play a role in bonding in the elements discussed. You can see my previous comment thread with Harry Gray for more details on this.
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