Final answer:
When water freezes into ice, the arrangement of the H₂O molecules changes, forming a crystalline structure.
Step-by-step explanation:
When water (H₂O) freezes into ice, a property of the H₂O that changes is the arrangement of the molecules. In the liquid state, water molecules are in constant motion and form weak hydrogen bonds with neighboring molecules, which allows the water to flow. However, when water freezes, the molecules slow down and arrange themselves in a regular pattern, forming a crystalline structure. This change in arrangement gives ice its solid state and characteristic shape.
Learn more about Freezing of water into ice