How do you find the charge on the complex ion?

How do you find the total charge of an ion?

• Answer:

  Example #1 - write the name for Fe(NO3)2 Step #1 - decide if the cation is one showing variable charge. If so, a Roman numeral will be needed. In this case, iron does show variable charge. If a variable charge cation is involved, you must determine the Roman numeral involved. You do this by computing the total charge contributed by the polyatomic ion. In this case, NO3¯ has a minus one charge and there are two of them, making a total of minus 2. Therefore, the iron must be a positive two, in order to keep the total charge of the formula at zero. Step #2 - determine the name of the polyatomic ion. Nitrate is the name of NO3¯. The correct name is iron(II) nitrate. The common name would be ferrous nitrate.