CAS CH 101 Lecture Notes - Lecture 16: Antibonding Molecular Orbital, Sigma Bond, Bond Order
4 Apr 2016
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Document Summary
For diatomics the mo can be obtained form solving the wave equation for h2+, the simplest molecule. Bonding waves interfere constructively between the nuclei, antibonding waves interfere destructively. For orbitals to combine they must: have significant overlap, be close in energy- this determines the strength of the interaction of the ao, interfering constructively for bonding and destructively for antibonding. The energy of the bonding mo shifts down, and the antibonding mo shifts up, compared to the ao, by an amount proportional to the strength of the interaction. N ao combine to produce n mo (# orbitals conserved). The different mo have no net overlap ( orthogonal ) Bond order = (# bonding e- - # antibonding e-) electrons in antibonding orbitals weaken the bond. End up with two molecular orbitals one bonding and one antibonding. Two 1s orbitals combing in-phase to give a bonding orbital. Two 1s orbitals combing out-pf- phase to give an antibonding orbital.
