Explain why ice floats on liquid water?

Ice floats because it is less dense than liquid water. When water freezes, molecules arrange into an open, hexagonal lattice held by hydrogen bonds, spacing them farther apart than in the liquid. More volume for the same mass means lower density, so ice stays on top.

How the structure of ice lowers its density

• Hydrogen bonds: Polar water molecules form H-bonds between O (δ−) and H (δ+).
• Crystal lattice: On freezing, H-bonds lock molecules into a stable, open hexagonal network.
• Greater volume: The ordered lattice leaves wide gaps; liquid water packs molecules closer.
• Lower density: More space per molecule → less density than liquid water.

Why density controls floating

• Buoyancy rule: An object floats if its density is less than the surrounding fluid.
• Water’s anomaly: Because ice is less dense than liquid water, it floats, creating an insulating surface layer that helps aquatic life survive in winter.