Calculate the formula mass of calcium iodate, ca (io3) 2, in atomic mass units (amu or u).

389.88094 amu First we look up the atomic mass of all elements contained in calcium iodate using the periodic table: Ca: 40.078 I: 126.90447 O: 15.999 As an intermediate step we calculate the molecular mass of the ion IO3: 126.90447 + 3*15.999 = 174.90147 Then we calculate the mass of one calcium atom and 2 iodate ions: 2*174.90147 + 40.078 = 389.88094 amu