The Chemistry of Water

Water consists of very small molecules. Each of them has two hydrogen atoms and one oxygen atom. The chemical formula of water is H2O.

Water can be a solid , a liquid or a gas, depending on the temperature it has. At 32° F (0° C) water freezes and turns into ice. It expands and becomes lighter. As a result ice floats on water. That is why you should let water out of pipes during the wintertime because it may freeze and burst the pipes. At 212°F (100°C) water boils and escapes as a vapor into the air. Between these two states water is a liquid. Most of the world’s water is in liquid form. It can be found everywhere on earth.

Water molecules always move. In ice they are very far apart from each other. They move very slowly or often not at all. Molecules in water vapor move very quickly.

Ice - water in its frozen form