covalent bond

The formation of a covalent bond between two hydrogen atoms to form a hydrogen molecule (H₂), and between two hydrogen atoms and an oxygen atom to form a molecule of water (H₂O). The sharing means that each atom has a more stable arrangement of electrons (its outer electron shells are full).

Chemical bond produced when two atoms share one or more pairs of electrons (usually each atom contributes an electron). The bond is often represented by a single line drawn between the two atoms. Covalently bonded substances include hydrogen (H₂), water (H₂O), and most organic substances.

Double bonds, seen, for example, in the alkenes, are formed when two atoms share two pairs of electrons (the atoms usually contribute a pair each); triple bonds, seen in the alkynes, are formed when two atoms share three pairs of electrons. Such bonds are represented by a double or triple line, respectively, between the atoms concerned. Covalent compounds have the following general properties: they have low melting and boiling points; do not conduct electricity; and are usually insoluble in water and soluble in organic solvents. Compare ionic compound.