Theory 07/Molecular & anomalous/Freezing expansion
Ice Floats Because Order Costs Density
The claim
Water expands on freezing because the ratio of open tetrahedral order to close packing in the solid exceeds that in the liquid, so the crystal is less dense than the melt.
01Mechanism
Hydrogen bonds impose a tetrahedral network with voids; the liquid retains some closer packing.
02Prediction
Expansion should track the order ratio.
03Refutation
Expansion tracking bond strength would remove geometry.