Chemical Bonding Basics
Part of the Chemistry For Dummies Cheat Sheet
In bonding, atoms lose, gain, or share electrons in order to have the same number of electrons as the noble gas that's nearest on the periodic table. Ionic, covalent, and metallic bonds are formed by combinations of metals and nonmetals.
Metal + nonmetal = ionic bond
Nonmetal + nonmetal = covalent bond
Metal + metal = metallic bond
When two elements engage in ionic bonding, one or more electrons are transferred from the metal to the nonmetal, forming ions (charged atoms). The metal, having lost one or more electrons, forms a cation, an ion with a positive charge; the nonmetal, having gained one or more electrons, becomes an anion, an ion with a negative charge.
When two elements form a covalent bond, one or more electron pairs are shared between these two elements. In metallic bonding, which occurs in metals (either a pure metal or an alloy of two or more metals), the valence (outer shell) electrons are donated to a "sea of electrons."