How does water change when it freezes?
In liquid form, water molecules move rapidly and stay close together. As the temperature drops to the freezing point, these molecules slow down and begin to form stable hydrogen bonds. Instead of huddling together, they arrange themselves into a hexagonal crystal structure. This specific geometric pattern forces the molecules to stay further apart than they were in the liquid phase. This expansion is the primary reason ice occupies more volume than the water it came from.
Why is ice less dense than liquid water?
Density is a measure of how much mass is packed into a specific volume. Because the crystal lattice of ice contains significant empty space between the molecules, a block of ice weighs less than an equal volume of liquid water. This decrease in density is unusual, as most substances become more compact and sink when they turn from a liquid to a solid. In water, the expansion during freezing ensures the solid form remains lighter than the liquid.
What role does buoyancy play in floating ice?
Buoyancy is the upward force exerted by a fluid that opposes the weight of an object. Since ice is less dense than the surrounding water, the water pushes the ice upward toward the surface. However, the difference in density between ice and liquid water is relatively small. This results in about ninety percent of an ice mass remaining submerged below the waterline, while only a small portion stays visible above the surface. This physical balance allows ice to stay afloat while most of its volume remains hidden.