Explicit science instruction
A useful molecular model should satisfy electron accounting and remain consistent with measured structural evidence. This investigation compares several candidate Lewis structures with a supplied data table.
Evaluate each candidate for total electron count, overall charge, connectivity, and whether predicted equivalent bonds agree with supplied bond-length patterns.
Do not select a model solely because it looks familiar. Preserve conflicting evidence and revise the representation when the data demand it.
Vocabulary: candidate model; bond length; evidence matrix; consistency check; model revision.
Worked example with reasoning
Two candidate structures both use the correct electron count, but only one predicts three equivalent C–O bonds consistent with the supplied equal bond lengths. That evidence favors the delocalized resonance model.
Guided question
Which evidence would most strongly distinguish two Lewis models that have the same total electron count but different predicted bond equivalence?
Independent work
- Audit three supplied candidate structures for electron count and charge.
- Compare their predicted bond patterns with a supplied bond-length table.
- Rank the models by evidence fit.
- Revise the strongest model if one observation remains unexplained.
Investigation / Data Lab
Preserve candidate structures, electron audits, bond evidence, model ranking, uncertainty, and one revision.
Misconception check
Correct electron counting is necessary but not sufficient; a model must also fit structural evidence.
Formative understanding check
Why can two Lewis drawings with correct electron counts still differ in quality?
Reveal response
They can differ in connectivity, formal-charge distribution, symmetry, or agreement with measured bond evidence.
Public self-check only.
Mentor evidence conference
Ask Archaemenes to audit your electron accounting, model assumptions, and evidence links.
Teacher guidance
Foundation: Use an evidence-matrix template.
Core: Compare several candidate structures using multiple criteria.
Extended: Explain where Lewis models remain inadequate even after the best candidate is chosen.
Return to Thursday Evidence