Single, Double, and Triple Bonds
So far, we’ve considered covalent bonds in which one pair of electrons is shared
between two atoms; these types of bonds are also called single bonds. In the
structural formula of a compound, a single bond is represented by a single line.
For example, water has two single bonds.
But more than one pair of electrons can be shared between atoms in a covalent
bond. If two pairs of electrons are shared, the bond is called a double bond. If
three pairs of electrons are shared, it is a triple bond. In general, as more pairs
of electrons are shared between atoms, the bond gets stronger and the distance
between bonded nuclei gets shorter. The oxygen molecule we looked at earlier
contains a double bond. It is represented by a double line, as follows: