Final answer:
To form a neutral ionic compound, one Ca²⁺ ion is needed to balance two Br⁻ ions, resulting in the chemical formula CaBr₂, which represents calcium bromide.
Step-by-step explanation:
To determine the number of Ca²⁺ and Br⁻ ions required to form a neutral ionic compound, one must understand the concept of charge balance in ionic compounds. Calcium ions have a charge of 2+, indicating each ion can balance two negative charges. Since bromide ions have a charge of 1-, two bromide ions are needed to balance the charge of one calcium ion. Therefore, the correct ratio for a neutral compound is one calcium ion to two bromide ions, and the resulting formula for the compound is CaBr₂.
The charge balance approach applied to ionic compounds ensures that the total positive charge equals the total negative charge, fulfilling the requirement for electrical neutrality. This underlines the importance of following the simple rule that the magnitude of the total positive charge in the compound should equal the magnitude of the total negative charge.