When water is melted, the hydrogen bonds between water molecules are broken. This is because the heat energy provided to melt the water causes the water molecules to move faster and collide with each other more frequently. This increased kinetic energy disrupts the hydrogen bonds, allowing the water molecules to move more freely. As a result, the water changes from a solid state to a liquid state.

The breaking of hydrogen bonds when water is melted has several important consequences. One consequence is that the density of water decreases. This is because the hydrogen bonds between water molecules cause them to pack more closely together in the solid state. When these bonds are broken, the water molecules can move further apart, resulting in a decrease in density. This is why ice floats on liquid water.

Another consequence of the breaking of hydrogen bonds when water is melted is that the surface tension of water decreases. Surface tension is the force that causes the surface of a liquid to resist breaking. In water, this force is caused by the hydrogen bonds between water molecules at the surface. When these bonds are broken, the surface tension of water decreases, making it easier for the surface to be broken. This is why water droplets form into spheres.

Finally, the breaking of hydrogen bonds when water is melted also affects the specific heat capacity of water. Specific heat capacity is the amount of heat energy required to raise the temperature of a substance by one degree Celsius. Water has a high specific heat capacity, meaning that it takes a lot of heat energy to raise its temperature. This is because the hydrogen bonds between water molecules store heat energy. When these bonds are broken, the stored heat energy is released, which raises the temperature of the water.