How can Ag2Cro4 have a four on the O? Ag has a charge of two, so multiplying it by 2 would give me two, but multiplying Cr, with a charge of two (one of its few choices) by four would give me eight. How does that balance? Thank you so muh for checking on this.
CrO4 is a polyatomic ion so it is one big part
the charge on it is -2
the 4 has nothing to do with it
if it were (CrO4)4 then it would be unbalanced