The Happiness of Chemistry

The noble gases in the rightmost group (column) of the periodic table – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – are all “happy” because they have filled outer shells. These elements are happy the way they are, and therefore seldom form bonds with other elements. Ah, but it’s a lonely existence for them.

The metals to the left of the zigzag staircase on the periodic table have one or more valence electrons, which makes them “unhappy.” They are eager to lose those electrons by forming ionic bonds with nonmetals. This way, their outer shells will be full, and they will be happy like the noble gases.

The nonmetals to the right of the zigzag staircase – except for the noble gases, of course – are equally unhappy. They wish to gain one or more electrons to fill their outer shells. Yes, all of the other elements are unhappy because they aren’t like the noble gases. So they bond in any way possible to try to fill their outer shells so that they, too, can feel like a noble gas.

Nonmetals can bond together with metals to form ionic bonds, or bond together with other nonmetals to form covalent bonds. (Sometimes, one or more atom groups are involved in the bond, in which case the bond consists of three or more atoms.)

When metal atoms and nonmetal atoms interact, the metal atoms donate their valence electrons to nonmetal atoms so that all of the atoms involved in the bonds have filled outer shells. The metal atoms become positively charged ions by losing electrons, while the nonmetal atoms become negatively charged ions by gaining electrons. These oppositely charged ions then attract one another.

For example, each sodium (Na) atom loses one electron and each chlorine (Cl) atom gains an electron when sodium and chlorine react together to form sodium chloride (NaCl). The positive Na⁺ ion attracts to the negative Cl^– atom in this ionic bond.

When two nonmetal atoms interact, they share valence electrons so that they both have the feeling of a filled outer shell. For example, carbon (C) bonds with four hydrogen (H) atoms in methane (CH₄). Carbon has 4 valence electrons, but feels the presence of 8 by sharing one electron with each hydrogen atom. Hydrogen has 1 valence electron, each but feels the presence of 2 by sharing one electron with carbon. Hydrogen needs 2 electrons to fill its outer shell, while carbon needs 8. This way, both carbon and hydrogen are happy through the covalent bond.

If only happiness were as simple to achieve in life as it is in chemistry. :-)

Chris McMullen, author of Understand Basic Chemistry Concepts and the Improve Your Math Fluency series of workbooks