Water is a fantastically unique molecule with many life supporting properties. Water molecules are made up of one oxygen and two hydrogen atoms. The bonds between these atoms are called covalent bonds because the atoms share electrons with each other. Due to the fact that electrons in water spend more time near the oxygen atom, the oxygen atom takes on a negative charge. The uneven charge of the atoms in a water molecule make it a polar molecule.
The atoms in water are covalently bonded to each other, but they are also bonded to other water molecules. Water molecules form hydrogen bonds between one another. These hydrogen bonds create the surface tension found in water. This surface tension is the reason insects are able to walk across the surface of a pond.