Valence electrons are outer shell electrons with an atom and can participate in the formation of chemical bonds. In single covalent bonds, typically both atoms in the bond contribute one valence electron in order to form a shared pair.
Covalent bonds are a class of chemical bonds where valence electrons are shared between two atoms, typically two nonmetals. The formation of a covalent bond allows the nonmetals to obey the octet rule and thus become more stable. For example: A fluorine atom has seven valence electrons.
