Final answer:
The correct formula for a compound made of calcium ions (Ca2+) and bromide ions (Br-) is CaBr2. This is because two bromide ions are needed to balance the 2+ charge of one calcium ion, resulting in a neutral compound.
Step-by-step explanation:
The correct formula for the compound containing calcium ions (Ca2+) and bromide ions (Br−) is CaBr2. This is due to the fact that calcium carries a 2+ charge and bromide carries a 1- charge. To balance the charges, two bromide ions are needed for every calcium ion, giving us CaBr2 as the proper ionic formula. Writing formulas for ionic compounds involves balancing the total positive charge with the total negative charge, ensuring the compound is electrically neutral.