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 Column 18 (VIIIA) noble gas elements such as He, Ar, and Ne contain complete outer electron shells (s2, p6) and do not commonly combine with other elements to form minerals. Instead, they tend to exist as monatomic (composed of single atoms) gases.

The periodic table is a highly visual and logical way in which to illustrate patterns in the electron configurations of the elements. Elements are grouped in rows or classes according to the highest principal quantum level in which electrons occur in the ground state. Elements are grouped into columns or groups based on similarities in the electron configurations in the higher principal quantum levels; those that are farthest from the nucleus and involved in most chemical reactions. More thorough explanations of the periodic table and the properties of elements are available in many standard texts in chemistry and physics.

From the discussion above, it should be clear that during the chemical reactions that produce Earth materials, elements display behaviors that are related to their electron configurations. Group 18 (VIIIA) elements in the far right column of the periodic table have stable electron configurations and tend to exist as uncharged atoms. Metallic elements toward the left side of the periodic table are strongly electropositive and tend to give up one or more electrons to become positively charged particles called cations. Nonmetallic elements toward the right side of the periodic table, especially in groups 16 (VIA) and 17 (VIIA), are strongly electronegative and tend to attract electrons to become negatively charged particles called anions. Elements toward the middle of the periodic table are somewhat electropositive and tend to lose various numbers of electrons to become cations with various amounts of positive charge. These tendencies are summarized in ssss1.