Labels:text | screenshot | font | line | diagram | number OCR: Formula Mass in grams is found with the help of the periodic table. A1C13 Aluminum Chloride is made up of 1 Al Ion and 3 13 Chloride Ions. From the periodic table we see A1 -Aluminum has a mass of approx. 27.0 units 26.982 Chlorine has a mass of approx. 35.5 units Aluminum Chloride consists of 1 A1 atom having 17 a mass of approx. 27 units and 3 atoms of chlorine C1 having a mass of approx 35.5 units. Adding we get 35.453 27 + 3(35.5) = 133.5 or about 133. A1C13 has a formula mass of 133 units One mole of A1C13 = 133 gms