Bond formation in water molecule. Illustration of the sharing of electrons (dots and crosses) between two hydrogen (H) and one oxygen (O) atom to form a molecule of water (H2O). This is an example of covalent bonding, with the two single bonds formed by a shared electron pair consisting of an electron from each atom. The outer electron shell of each atom is shown as a blue ring. Water is a liquid at room temperature and pressure. The bonds are not shown here. For the fully bonded molecule, see image C028/6477.