What is a covalent bond?

A covalent bond in an intramolecular bond which occurs when a pair of electrons is shared between two elements, usually two non-metals. The electrons shared are in the outer shell of the atom of each element, which each atom contributing one electron to the shared pair, leaving both atoms with a complete outer shell. Covalent bonding can be represented with dot and cross diagrams and displayed formula. Examples of molecules with covalent bonds include H₂O, CO₂ and H₂.