7.1. Ionic Compounds http://www.ck12.org
The crisscross method first yields Pb 2 O 4 for the formula, but that must be reduced to PbO 2 , which is the correct
formula.
Click here to watch an animation of ionic bonding: http://www.dlt.ncssm.edu/core/Chapter9-Bonding_and_Geome
try/Chapter9-Animations/IonicBonding.html.
Sample Problem 7.1: Writing Formulas for Binary Ionic Compounds
Write the correct formulas for the following ionic compounds:
- barium chloride
- chromium(III) oxide
Step 1: Plan the problem.
In each case, write the metal cation followed by the nonmetal anion. Crisscross the ion charges in order to make
each ionic compound neutral. Reduce to the lowest ratio if necessary.
Step 2: Solutions.