Learning Objectives Explain the bonding nature of ionic compounds. Relate microscopic bonding properties to macroscopic solid properties. Neutral atoms and their associated ions have very different physical and chemical properties. Sodium atoms form sodium metal, a soft, silvery-white metal that burns vigorously in air and reacts explosively with water. Chlorine atoms form chlorine gas, Cl 2 , a yellow-green gas that is extremely corrosive to most metals and very poisonous to animals and plants. The vigorous reaction between the elements sodium and chlorine forms the white, crystalline compound sodium chloride, common table salt, which contains sodium cations and chloride anions (Figure \(\PageIndex{1}\)). The compound composed of these ions exhibits properties entirely different from the properties of the elements sodium and chlorine. Chlorine is poisonous, but sodium chloride is essential to life; sodium atoms react vigorously with water, but sodium chloride simply dissolves in water. Ionic Bonds When two atoms approach each other, they have the potential to bond (or connect). If a metal and a nonmetal interact, then an ionic bond will result. These types of bonds involve the metal donating it(s) valence electron(s) to a nonmetal. As the electronic transfer occurs, both atoms will achieve more stable confirmations. The end result will be a less reactive compound. These type of species are composed of both cations and anions. In addition, they are crystalline and solid in nature (Figure \(\PageIndex{2}\)) . A few examples of real-world ionic compounds would be NaCl (table salt) and NaF (active ingredient in toothpaste). The formula for table salt is NaCl. It is the result of Na + ions and Cl - ions bonding together (Figure \(\PageIndex{3}\)) . If sodium metal and chlorine gas mix under the right conditions, they will form salt. The sodium loses an electron, and the chlorine gains that electron. This reaction is highly favorable because of the electrostatic attraction between the particles. In the process, a great amount of light and heat is released. The resulting salt is mostly unreactive — it is stable. It will not undergo any explosive reactions, unlike the sodium and chlorine that it is made of. Figure \(\PageIndex{2}\) NaCl crystals. (Public Domain; NASA). The reaction is represented with Lewis dot symbols below. Chloride Salts The sodium atom is donating its 1 valence electron to the chlorine atom. This creates a sodium cation and a chlorine anion. Notice that the net charge of the resulting compound is 0. Summary An ionic bond is formed when a metal donates it(s) valence electron(s) to a nonmetal. The resulting ionic compound is more stable and less reactive. References Vollhardt, K. Peter C., and Neil E. Schore. Organic Chemistry Structure and Function . New York: W. H. Freeman, 2007. Petrucci, Ralph H. General Chemistry: Principles and Modern Applications . Upper Saddle River, NJ: Pearson Education, 2007. Brown, Theodore L., Eugene H. Lemay, and Bruce E. Bursten. Chemistry: The Central Science . 6th ed. Englewood Cliffs, NJ: Prentice Hall, 1994.