A chemical bond is any force of attraction between two atoms strong enough to hold the atoms together for some period of time. At least five primary types of chemical bonds are known, ranging from very strong to very weak. They are covalent, ionic, metallic, and hydrogen bonds, and London forces.

In all cases, a chemical bond ultimately involves forces of attraction between the positively-charged nucleus of one atom and the negatively-charged electron of a second atom. Understanding the nature of chemical bonds has practical significance since the type of bonding found in a substance explains to a large extent the macroscopic properties of that substance.

An ionic bond is one in which one atom completely loses one or more electrons to a second atom. The first atom becomes a positively charged ion and the second, a negatively charged ion. The two ions are attracted to...