Determining the Charge on a Variable Charge Cation—Au2S3

• Determine the charge on the anion.

Au2S3 : the anion is S, since it is in Group 6A, its charge is 2−.

• Determine the total negative charge.

Since there are 3 S in the formula, the total negative charge is 6−.

• Determine the total positive charge.

Since the total negative charge is 6−, the total positive charge is 6+.

• Divide by the number of cations.

Since there are 2 Au in the formula and the total positive charge is 6+, each Au has a 3+ charge.