Fill in the missing information to give formulas for the fol-lowing compounds: (a) Na?SO4 (b) Ba?(PO4)? (c) Ga?(SO4)?

Ionic compounds are formed from the electrostatic attraction between positively charged cations and negatively charged anions. In the context of the question, understanding how to identify the charges of common ions, such as Na+, Ba2+, and PO4^3-, is essential for determining the correct formulas of the compounds listed.

Polyatomic ions are ions composed of two or more atoms that are covalently bonded and carry a net charge. For example, sulfate (SO4^2-) and phosphate (PO4^3-) are common polyatomic ions. Recognizing these ions and their charges is crucial for correctly writing the formulas of compounds that include them.

In ionic compounds, the total positive charge must balance the total negative charge to achieve electrical neutrality. This principle is vital when determining the correct subscripts in the formulas. For instance, if a compound contains a divalent cation like Ba2+, it will require two monovalent anions like SO4^2- to balance the charges.