Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair. Ion Na+ Ca2+ Fe2+ Al3+ O2- Na2O NO3- SO42- AsO43-

Key Concepts

Ionic Compounds

Ionic compounds are formed through the electrostatic attraction between cations (positively charged ions) and anions (negatively charged ions). The overall charge of the compound must be neutral, meaning the total positive charge from cations must balance the total negative charge from anions. This principle is essential for determining the correct formula of the compound.

Charge Balance

Charge balance is a fundamental concept in forming ionic compounds, where the sum of the charges from cations and anions must equal zero. For example, a Ca2+ cation requires two O2- anions to achieve neutrality, resulting in the formula CaO. Understanding how to balance these charges is crucial for writing correct chemical formulas.

Polyatomic Ions

Polyatomic ions are ions composed of two or more atoms that carry a net charge. Examples include nitrate (NO3-) and sulfate (SO42-). When forming ionic compounds, the presence of polyatomic ions requires careful consideration of their charge and how they combine with cations to ensure overall charge neutrality in the resulting formula.