SCIENCE · INVESTIGATE AND EXPLAIN

Separate donor identity, acceptance and contact geometry

Apply an explicit screening rule without mistaking it for a universal measured interaction definition.

Learning outcome: Compare water→ether with ether→water at180°, then reduce the water→ether angle below the declared150° screen. Retain identity and geometry flags separately.

Starting recap

Review the electron and formal-charge budget, bond multiplicity, signed interaction energies and the distinction between a model and a measured property.

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Try

Water can donate O–H to ether oxygen even though ether lacks an O–H donor; reversing the proposed donor role fails this introductory packet rule.

Open the experiment

Predict

Does lacking an O–H bond prevent an ether from accepting a hydrogen bond from water?

Your prediction and reason

Experiment

Compare water→ether with ether→water at180°, then reduce the water→ether angle below the declared150° screen. Retain identity and geometry flags separately.

Check donor identity, acceptor and a geometric rule

Worked teaching model · synthetic values · Original fixed-distance 290 pm donor–acceptor packets: water→water, ammonia→water, water→ether, methane→water, ether→water with ether incorrectly proposed as the donor. This introductory N/O/F donor rule and angle≥150° are explicit screening criteria, not universal physical hydrogen-bond definitions or measured energies.

Contact packet: 0 choice D–H···A angle: 180 degrees

Reset keeps your prediction, captures and practice history.

Solid D–H indicates the proposed covalent donor bond; dotted H···A is only the proposed contact. An unsuitable donor remains unsuitable even if the diagram is straight.

Calculated evidence under the declared representation
Quantity	Value	Unit
Introductory donor criterion	1	flag
Available acceptor in packet	1	flag
Declared angle screening criterion	1	flag
All declared criteria satisfied	1	flag
Donor–acceptor distance	290	pm
D–H···A angle	180	degrees

water O–H donor → water O acceptor

An ether can accept a hydrogen bond from water despite lacking its own O–H donor. The introductory donor rule excludes the methane contact here without asserting that all weak C–H contacts are universally impossible. Passing a screening rule is not a measured binding energy, lifetime, equilibrium abundance or complete interaction network.

water O–H donor → water O acceptor

Observation to attach to a capture

Captures preserve recipes and replay their calculated results. They are synthetic model evidence, not physical measurements.

Understand

Distinguish the two bonds in the picture

In the introductory hydrogen-bond description, a hydrogen is covalently bound to a suitable donor atom such as nitrogen, oxygen or fluorine and interacts with an available acceptor. The donor’s covalent bond is not the same interaction as the intermolecular contact. The acceptor need not have its own hydrogen attached.

Roles are directional

Water can donate an O–H contact to an ether oxygen with an available lone pair. The same ether lacks an O–H donor, so reversing the proposed roles is not equivalent. Ammonia can provide an N–H donor in the supplied water-contact packet. Protonation, resonance and chemical environment can change acceptor availability; the mere existence of a drawn lone pair is not a universal guarantee of equivalent behavior.

Declare the screening rule

Our original packets fix donor–acceptor distance at290 pm and use an introductory donor-identity criterion plus a D–H···A angle of at least150°. Straight180° and bent120° arrangements therefore differ under this deliberately chosen screen. The cutoff is a data-screening rule, not a fundamental discontinuity in interaction energy or a universal definition of hydrogen bonding.

Predict before inspecting flags

At180°, the water→ether packet passes the supplied identity and angle checks. At120°, the identities remain suitable but the declared geometry screen fails. Ether→water fails the donor check even at180°. Keep these separate reasons; changing a geometric control cannot create a missing donor group. The methane packet is excluded by this introductory N/O/F donor convention, without asserting that every weaker C–H contact in advanced chemistry is impossible.

Avoid network overclaims

A passing pair does not establish an interaction lifetime, measured binding energy or how many contacts are simultaneously realized in a liquid. Steric constraints, competition and thermal motion affect a network. Intramolecular contacts can also compete with contacts between molecules. A good explanation specifies the donor, acceptor, geometry rule and evidence level instead of counting every lone pair as an independently guaranteed bond.

Sources and evidence boundary

Conceptual sources checked 30 October 2026: Hydrogen bonding and other forces. All prose, cases, code and diagrams are original. The supplied models are not measured structures, a performed laboratory investigation or certification of independent mastery. No chemical handling, heating, pressure vessel or cryogenic experiment is requested. Retain predictions, contrasting evidence and a changed-case explanation.

Apply

Public practice checks a specific claim. It does not establish independent mastery.

What does passing a geometric screening criterion fail to establish about energy, lifetime or a whole-liquid network?

Your explanation and limitations

Continue

Completion requires a saved prediction, at least one capture and a reflection. Presence checks do not grade your reasoning.

Skipping retains experiments and awards no mastery.

Previous: Compare dispersion contacts without a mass-only shortcut Next: Distinguish equilibrium vapor pressure from evaporation speed

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