Final answer:
Ice floats on water because as water freezes and turns into ice, it expands and becomes less dense due to the formation of a crystalline structure by its molecules. This counter-intuitive behavior does not match with the kinetic theory of matter which suggests the particles would be closer and denser in the solid state.
Step-by-step explanation:
The expectation from the kinetic theory of matter is that as a substance cools down and turns from a liquid to a solid, the particles move less and become denser, therefore causing the solid phase to sink in the liquid phase. This is because the particles in a solid are typically packed closely together. However, ice floats on water because water is an unusual substance that expands as it freezes. This expansion causes ice to have a lower density than liquid water, which causes it to float.
When water freezes into ice, the water molecules form a crystalline structure maintained by hydrogen bonds. This causes each water molecule to be at a greater distance from its neighbors than when it was liquid. As a result, ice is less dense than the water from which it forms and so it floats on the surface of the water.
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