What occurs when water freezes?

When water freezes, it undergoes a unique phase change from liquid to solid. During this process, water expands instead of contracting, which is an unusual behavior for most substances. The reason for this expansion lies in the molecular structure of ice.

As water molecules cool down and begin to freeze, they arrange themselves into a crystalline structure that takes up more space than the disordered arrangement of molecules in liquid water. This organized lattice structure is held together by hydrogen bonds, which compel the molecules to maintain a certain distance apart, resulting in a lower density for ice compared to liquid water.

This property has significant implications in nature; for instance, ice floats on water, which provides insulation for aquatic ecosystems in cold conditions. The expansion of freezing water is critical for understanding various environmental processes and has important consequences for the climate and ecology.