Final answer:
The crisscross method is an alternative way to write correct formulas for ionic compounds. It involves crossing over the numerical values of the ion charges to become the subscripts of the other ion. The signs of the charges are dropped.
Step-by-step explanation:
Crisscross Method for Writing Ionic Compound Formulas
The crisscross method is an alternative way to write correct formulas for ionic compounds. It involves crossing over the numerical values of the ion charges to become the subscripts of the other ion. The signs of the charges are dropped.
Example:
Let's write the formula for lead (IV) oxide using the crisscross method:
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- Write the symbol and charge of the cation (metal) first, which is Pb4+
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- Write the symbol and charge of the anion (nonmetal) second, which is O2-
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- Crisscross the numerical values of the ion charges: 4 becomes the subscript for O, and 2 becomes the subscript for Pb
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- The formula for lead (IV) oxide is PbO2