<unk> s a form  of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, or between atoms and other<unk> s. In short, attraction-to-repulsion stability that forms between atoms when they share electrons is known as<unk> ing.<unk> ing includes many kinds of interactions, including σ-bonding, π-bonding, metal-metal bonding, agostic interactions, and three-center two-electron bonds. The term<unk>  dates from 1939. The prefix co- means jointly, associated in action, partnered to a lesser degree,  etc.; thus a "co-valent bond", essentially, means that the atoms share "valence", such as is discussed in valence bond theory. In the molecule H2, the hydrogen atoms share the two electrons via<unk> ing.<unk> y is greatest between atoms of similar electronegativities. Thus,<unk> ing does not necessarily require the two atoms be of the same elements, only that they be of comparable electronegativity.  Because<unk> ing entails sharing of electrons, it is necessarily delocalized. Furthermore, in contrast to electrostatic interactions ("ionic bonds") the strength of<unk>  depends on the angular relation between atoms in polyatomic molecules.
Covalent bond
Disulfide bond
Carbon-carbon bond
Resonance
Van der Waals strain
Glycosidic bond
Organic reaction
Host-guest chemistry