Formula Mass and the Mole Concept for Compounds

In Chapter 2, we defined the average mass of an atom of an element as its atomic mass. Similarly, we now define the average mass of a molecule (or a formula unit) of a compound as its formula mass. (The terms molecular mass or molecular weight are synonymous with formula mass and are also common.) For any compound, the formula mass is the sum of the atomic masses of all the atoms in its chemical formula. 

To find the formula mass, add the atomic masses of each atom in the chemical formula  

---