WHY ICE FLOATS IN WATER
HAVE YOU WONDERED WHY ICE FLOATS IN WATER?
The fact that ice floats in water is a bit strange, because most substances are denser when they are solids. Water, however, reaches its maximum density at 40º F (4.4º C). As water cools and freezes, it becomes less dense due to the unique nature of hydrogen bonds.
Water molecules tend to be attracted to each other by weaker hydrogen bonds. These form between the positively-charged hydrogen atoms and negatively-charged oxygen atoms in nearby water molecules.
As water temperature decreases, the weaker hydrogen bonds begin to hold the negatively-charged oxygen atoms apart, forming a rigid crystal honeycomb structure we call ice. The water molecules in ice take up about 9% more space than liquid water, which means ice is about 9% less dense than water.
If you have a gallon of ice and a gallon of water, the gallon of ice will weigh less than the gallon of water. When you put the ice into the water, the denser water pushes the ice to the top where it will float.
This unique property of water is especially beneficial for fish that live in bodies of water that freeze in the winter. Because ice floats, bodies of water freeze from top to bottom. This allows fish to survive deep underwater even when the surface freezes.