Question

what happens to water molecules as ice melts

Answer 1

Imagine a crowded dance floor.

Imagine a line dance. Notice how the people are in one organized grid, each moving about their own localized zone of the floorspace? Make this analogous to the solid phase of matter.


Now imagine instead of an organized grid, that you just have the people dancing freely everywhere and pushing their way through each other. All floorspace is occupied (mostly)...not really much room for many more new people to join. Make this analogous to the liquid phase of matter.


NOTHING actually happens to individual molecules. No molecules themselves do any expanding or contracting, and no molecules themselves change at all.

ONLY the intermolecular bonding changes, becoming a bit weaker due to more energy per molecule (more rapid vibrations).

The "contracting" during melting is not the molecules themselves being compressed, but rather, the space between being more occupied.


Water ice is unique in its crystal. Do not expect any other substance to undergo this unique sparse as a solid, dense as a liquid property.

In fact, most other substances do the opposite (denser as a solid than as a liquid).
source : https://answers.yahoo.com/question/index?qid=20110114225007AAU0xi8