What is the chemical formula for water?
The chemical formula for water is H₂O. Each water molecule is made of two hydrogen atoms bonded to one oxygen atom, in a bent shape.
The two hydrogen atoms attach to the oxygen at an angle of about 104.5 degrees. Oxygen pulls the shared electrons more strongly than hydrogen does, so the oxygen end of the molecule has a slight negative charge and the hydrogen ends a slight positive charge. Molecules like this are called polar.
Because of this polarity, water molecules stick to each other through hydrogen bonds. These bonds explain many of water's unusual properties: its high boiling point for such a small molecule, the surface tension that lets insects walk on ponds and the fact that ice floats.
The universal solvent
Water dissolves more substances than almost any other liquid, which is why it is often called the universal solvent. In our bodies, it carries nutrients, salts and waste. The formula H₂O was confirmed in the early 1800s, after scientists showed that water could be split into two parts hydrogen and one part oxygen.
Did You Know?
Heavy water, D₂O, contains a heavier form of hydrogen called deuterium. It looks like normal water but is about 11 percent denser, and an ice cube made from it sinks in ordinary water.