ABSTRACT
At its core, chemistry, as the study of matter and change, is intimately centered on the chemical bond. A bond is the energy that holds atoms together, thus defining all matter aside from monatomic gases, and bonds are made and broken in a chemical reaction. This chapter takes a deeper look at the two types of chemical bonds: ionic and covalent. Ionic bonds arise from the electrostatic attraction between ions (as modeled by Coulomb's law). Covalent bonds, by contrast, involve the sharing of electrons between two atoms. Covalent compounds are often represented by Lewis structures, where a shared pair of electrons is drawn as a line. Covalent bonding is best explained by using quantum mechanics. Two complementary theories are used to explain bonding: valence bond (VB) theory and molecular orbital (MO) theory. In both theories, a covalent bond forms when atomic orbitals overlap to form new, lower energy, bonding molecular orbitals. This orbital mixing also gives rise to high-energy antibonding orbitals, the existence of which can explain spectroscopic and chemical phenomena.
