Ice

Ice, frozen water; colorless crystalline solid in which the strong, directional hydrogen bonding produces a structure with much space between the molecules. Thus ice is less dense than water and floats on it. The expansion of water on freezing may crack pipes and automobile radiators. Seawater freezes at about 28°F (−2°C). Ice has a very low coefficient of friction, and some fast-moving sports (ice hockey and ice skating) are played on it; slippery, icy roads are dangerous. Ice deposited on airplane wings reduces lift. Ice is used as a refrigerant and to cool some beverages.

See also: Water.