What's the chemical symbol for water?

The chemical symbol for water is H2O. This formula means that each water molecule contains two hydrogen atoms bonded to one oxygen atom.

Water’s unusual behavior comes from the shape and polarity of that molecule. Its oxygen atom attracts electrons more strongly than hydrogen does, giving water partial positive and negative ends. This polarity helps water dissolve many substances and allows neighboring molecules to form hydrogen bonds.

H2O describes pure water, but natural water usually contains dissolved minerals, gases, or salts. Ice and water vapor are still H2O; only the physical arrangement and energy of the molecules change. A common mix-up is confusing a chemical formula with a chemical symbol: H is the symbol for hydrogen and O is the symbol for oxygen, while H2O is the molecular formula for the compound water. The number 2 applies only to hydrogen because there are two hydrogen atoms for every oxygen atom.