The elements having less than 8 electrons in their outermost shell always have a tendency to attain an octet in order to attain a noble gas configuration by gaining or losing electron forming ionic compounds. They gain or lose electrons to attain the nearest noble gas configuration by sharing valence electrons present in their outermost shell with the electrons in the outermost shell of the combining atoms of other elements.

Due to this sharing of four electrons of atom of element with the electrons of other combining atoms an element is said to form covalent bonds. Compounds possessing covalent bonds have strong bonds within the molecule, but intermolecular forces are small leading to low melting and boiling points of these compounds. Due to the sharing of electrons no charged particles are formed i.e. no ions are formed due to which covalent compounds are poor conductors of electricity.

For example, Carbon forms covalent bond.