Nonmetal atoms within a covalent molecule are held together by covalent bonds. Covalent bonds are formed when atoms share one or more pairs of electrons. The electrons that are shared are held in a region of space between the atoms, called the molecular orbital. The molecular orbital is formed when the atomic orbitals of the individual atoms overlap.

The strength of a covalent bond depends on the number of electron pairs that are shared, and the distance between the atoms. The more electron pairs that are shared, the stronger the bond. The shorter the distance between the atoms, the stronger the bond.