Explicit science instruction
A complete IMF explanation starts with molecular structure, identifies all relevant interactions, compares size and shape, and then predicts a measurable property.
Use matched data when available and state confidence. Strong reasoning avoids single-label shortcuts such as 'hydrogen bond means highest boiling point.'
Structure–property claims are comparative: the same interaction can matter differently depending on molecular size, number of sites, and geometry.
Vocabulary: structure–property; interaction hierarchy; matched evidence; prediction; limitation.
Worked example with reasoning
A small alcohol and an ether of similar molar mass differ in donor ability. The alcohol’s additional hydrogen-bond network can raise its boiling point relative to the ether, while both still experience dispersion.
Guided question
Write a CER predicting which of two supplied molecules should evaporate more slowly and explain at least two structural factors.
Independent work
- Rank four molecules by expected intermolecular attraction.
- Check the ranking against supplied boiling data.
- Write a CER and identify one uncertainty.
- Record one corrected shortcut from the week.
Spiral retrieval bridge
- From Week 09: how can structure alter conductivity?
- From Week 08: how does geometry affect molecular polarity?
- From Week 07: distinguish resonance from molecular flipping.
- From Week 05: use electronegativity to justify one bond dipole.
Misconception check
IMF names are tools for explaining patterns, not a guaranteed property ranking by themselves.
Formative understanding check
What makes an IMF prediction stronger than simply naming the strongest interaction?
Reveal response
It integrates all relevant interactions, size/shape, and matched evidence.
Mentor evidence conference
Ask Archaemenes to test whether your structure–property claim controls competing variables.
Teacher guidance
Foundation: Use a comparison sentence frame.
Core: Integrate structure, IMF types, and property data.
Extended: Defend a difficult ranking where size and hydrogen bonding compete.