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8.10: Arrhenius Acids and Bases: Introduction to Writing Chemical Formulas and Names of Arrhenius Bases

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  • The previous sections of this chapter presented and applied two patterns that could be used to determine the chemical formulas and names of hydrohalogenated, "HX," and polyatomic, "HNPoly" Arrhenius acids, which contain one or more protons and either monatomic or polyatomic anions, respectively.

    Recall that Arrhenius prepared aqueous solutions so that he could study the ionizations of strong and weak electrolytes, which dissociate, or separate, into cations and anions when dissolved in water.  During his investigations, Arrhenius found that specific types of electrolytes produced hydroxide ions, OH–1, when dissolved in water.  While the number of solutes that can dissociate to form hydroxide ions are limited, relative to the quantity of molecules that ionize to produce protons, Arrhenius still considered this generation of hydroxide ions as a chemically-significant phenomenon and classified the electrolytes that initially contained these particles as "bases."  However, since, as stated above, strong and weak electrolytes must generate both cations and anions when dissolved in a solvent, an Arrhenius base must, by definition, contain a hydroxide ion, OH–1and a component that ionizes to produce a stable, positively-charged particle.

    Finally, because all Arrhenius bases contain hydroxide ions, the chemical formula and name of a specific Arrhenius base is dependent on the identity of the cation that it contains.  Polyatomic, or multi-atom, cations are units that bond as indivisible charged entities and have defined formulas, names, and charges.  However, because very few stable polyatomic cations exist, these positively-charged units are not commonly found in Arrhenius bases.  In contrast, a significant number of monatomic, or single-atom, cations can be generated from metals that lose valence electrons to achieve octet configurations.  The pattern for determining the chemical formulas and names of Arrhenius bases that contain these monatomic cations will be presented and applied in the following section of this chapter.