Naming ionic compounds

When you name inorganic compounds, you write the name of the metal first and then the nonmetal, adding an -ide ending to the nonmetal (for compounds involving monatomic ions). Suppose, for example, that you want to name Li₂S, the compound that results from the reaction of lithium and sulfur.  You first write the name of the metal, lithium, and then write the name of the nonmetal, adding an -ide ending so that sulfur becomes sulfide:

Li₂S: Lithium sulfide

Ionic compounds involving polyatomic ions follow the same basic rule: Write the name of the metal first, and then simply add the name of the nonmetal. However, with polyatomic anions, it’s not necessary to add the -ide ending:

(NH₄)₂CO₃: Ammonium carbonate

K₃PO₄: Potassium phosphate