PO4^3- is the phosphate polyatomic ion. What is the name for the ionic compound Fe3(PO4)2

Note: Fe can be ionized to Fe2+ or Fe3+. The 1st 4, 2nd 3, 2nd 4, and 1st 2 are all written smaller than everything else.

Think about how the compound is put together by "undoing" the criss-cross rule. That is, move the opposing subscripts to the superscript of the opposite element or compound -- this will reveal how it was put together. This is illustrated as follows: 2 goes to Fe, 3 goes "back" to the PO43-.

In other words, the ions for this compound are: Fe2 + PO43-, also known as IRON (II) PHOSPHATE.