Water boils when the thermal energy in the water, which is a type of kinetic energy which causes the water molecules to move around, exceeds the strength of the hydrogen bonds between the molecules, causing them to separ... More »

Mercury, the only metal that remains liquid at room temperature, is more than 13 times denser than water. One way of comparing densities of liquids is by combining them to determine which floats on top of the other. Howe... More »

When water freezes, the molecules slow down and assume a fixed position, although not quite in the way that one might think. Water is made of molecules with two hydrogen atoms and an oxygen atom, but those molecules don'... More »

Water freezing into ice is a physical change because the hydrogen and oxygen molecules that make up the water stay the same, despite the change in state from liquid to solid. A physical change is simply a change in the m... More »

Water boils once the temperature reaches 212 degrees Fahrenheit or 100 degrees Celsius. In contrast, water freezes at 32 F or 0 C. More »

Water begins to evaporate whenever its molecules speed up enough to break free from their bonds. A water molecule, or H20, is made of two hydrogen atoms and one oxygen atom. More »

Water evaporates when molecules at the interface of water and air have enough energy to escape the forces that hold them together in the liquid. Evaporation, along with boiling, is a type of vaporization. More »

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