K2CrO4 = potassium chromate, ionic, 2moles of K atoms, 1mole of Cr atoms, 4 moles of O atoms
moles atoms x 6.022x10^23atoms/mole = number of atoms
2BaCl2 = barium chloride, ionic, 2moles Ba atoms, 4 moles Cl atoms
you do the rest, remember coefficients are multiplied through the entire compoud
subscripts are multiplied only for that element they are with, if the subscript is outside of a (), it gets multiplied through the entire ()
