Multiple Bonds

In a covalent bond, atoms can share more than one pair of electrons. For example, in an oxygen molecule, each oxygen atom has six valence electrons. If only one pair of electrons was shared, then each atom would only have seven electrons, one short of the eight needed for a full octet. To make an octet, each oxygen atom needs two additional electrons added to its current six. In order to gain two more electrons, each atom must share two electrons with the other atom, so that there are four electrons being shared. The covalent bond formed by sharing two pairs of electrons is known as a double bond. Single or multiple bonds will for, depending on how many electrons the atom needs to complete an octet. Triple bonds may also be formed, a triple bond of course being a covalent bond in which two atoms share three pairs of electrons.