H3 Chemistry 9813 · Study focus: H3 Chemistry: Classify bonding, antibonding and nonbonding orbitals
H3 Chemistry: Classify bonding, antibonding and nonbonding orbitals
Start from the governing chemical model, test it against evidence, then transfer the reasoning to an unfamiliar case.
Your success criteria
- Classify bonding, antibonding and nonbonding orbitals
- Use named chemical evidence.
- Transfer the governing reason to an unfamiliar case.
Orientation and prerequisite retrieval
In-phase overlap increases density between nuclei and produces a lower-energy bonding MO.
Out-of-phase overlap introduces an internuclear node and produces a higher-energy antibonding MO.
Definitions and exact language
A nonbonding orbital has little net stabilising or destabilising overlap in the bonding interaction considered.
The star in σ* or π* denotes antibonding character, not an excited electron by itself.
A node between the nuclei is decisive evidence of antibonding interaction for the paired AOs.
Bonding and antibonding partners arise from the same compatible AO pair with opposite phase combinations.
Text alternative: Text alternative: Electrons in bonding MOs stabilise the molecule relative to separated atoms. A labelled sketch must show both phase relationship and any node needed to justify the classification.
Detailed molecular explanation
A node between the nuclei is decisive evidence of antibonding interaction for the paired AOs.
Bonding and antibonding partners arise from the same compatible AO pair with opposite phase combinations.
Worked leaf-specific case
Electrons in bonding MOs stabilise the molecule relative to separated atoms.
Electrons in antibonding MOs oppose bonding density and reduce net bond order.
- A candidate writes, “In-phase overlap creates an internuclear node.” Which correction should replace it?
Open the feedback checkpoint after attempting
- In-phase overlap increases density between nuclei and produces a lower-energy bonding MO.
Guided evidence check
A nodal plane required by π symmetry is not by itself the internuclear antibonding node.
Orbital phase signs describe wavefunction phase, not positive and negative electrical charges.
- Which labelled diagram, spectrum or calculation would most directly disprove “A star means an electron has absorbed a photon.”?
Open the feedback checkpoint after attempting
- The star in σ* or π* denotes antibonding character, not an excited electron by itself.
Independent transfer
Bonding classification depends on density and energy relative to the parent AOs.
A labelled sketch must show both phase relationship and any node needed to justify the classification.
- Design a specific chemical check that would expose the error in “An electron in a bonding MO destabilises the molecule.”
Open the feedback checkpoint after attempting
- Electrons in bonding MOs stabilise the molecule relative to separated atoms.
Misconception repair
Misconception: The words bonding and antibonding are assigned without comparing energy or density.
Repair: Bonding classification depends on density and energy relative to the parent AOs.
- Write leaf-specific feedback for the misconception “The words bonding and antibonding are assigned without comparing energy or density.”
Open the feedback checkpoint after attempting
- Bonding classification depends on density and energy relative to the parent AOs.
Practice, unseen assessment, re-test and next step
Complete the diagnostic questions, review the feedback, then attempt the final check.
After delayed re-test, continue to Distinguish molecular orbitals with sigma and pi symmetry at /learning/h3-molecular-orbitals-sigma-pi-symmetry-lesson.html.
- Review the feedback for each diagnostic question, then attempt the final check.
Open the feedback checkpoint after attempting
- Before moving on, state this boundary: A labelled sketch must show both phase relationship and any node needed to justify the classification.