Energy differences of molecular orbitals

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Discussion Overview

The discussion revolves around comparing the energy differences of molecular orbitals, specifically between the 1s antibonding orbital and the 2s bonding orbital in different molecular configurations, such as A-A and A-B. The scope includes theoretical aspects of molecular orbital theory and its application in understanding molecular structures.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions how to compare the energy differences between the 1s antibonding orbital and the 2s bonding orbital.
  • Another participant asserts that antibonding orbitals are generally higher in energy than bonding orbitals and mentions the construction of MO diagrams as a skill taught in inorganic chemistry.
  • A participant challenges the claim about the energy levels, asking if the 1s antibonding orbital is indeed higher in energy than the 2s bonding orbital.
  • A subsequent reply expresses doubt about the original question's validity, indicating confusion over the energy comparison.
  • A later contribution cites a textbook stating that for homonuclear diatomic molecules of the first 10 elements, the 2s-2s bonding orbitals are higher in energy than the 1s-1s antibonding orbitals.

Areas of Agreement / Disagreement

Participants express disagreement regarding the energy levels of the molecular orbitals in question. There is no consensus on the comparison between the 1s antibonding and 2s bonding orbitals, and the discussion remains unresolved.

Contextual Notes

There are limitations regarding the assumptions made about molecular orbital energy levels, and the discussion references specific cases (homonuclear diatomic molecules) without addressing broader contexts or exceptions.

Helena Wells
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Suppose we have a molecule A-A and a molecule A-B . And we want to compare the differences in energy of the different molecular orbitals for example the 1s antibonding orbital with the 2s bonding orbital.How can we do that?
 
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Antibonding orbitals are higher in energy than bonding orbitals. you can construct MO diagrams by following certain rules. at my university the skill is taught in inorganic chemistry
 
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docnet said:
Antibonding orbitals are higher in energy than bonding orbitals. you can construct MO diagrams by following certain rules. at my university the skill is taught in inorganic chemistry
I don't think that is true . Are you saying the 1s antibonding orbital has higher energy than the 2s bonding orbital?
 
Helena Wells said:
I don't think that is true . Are you saying the 1s antibonding orbital has higher energy than the 2s bonding orbital?
I was mistaken. Now I don't think the question makes any sense.
 
Here you go. My textbook says 2s-2s bonding orbitals are higher in energy than the 1s-1s antibonding orbitals for homonuclear diatomiicc molecules of the first 10 elements, from H to Ne.
Screen Shot 2021-02-21 at 5.52.43 PM.png
 

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