mass of 40 amu and accounts for 60% of naturally occurring Q. The atomic mass of
isotope B is 44 amu and accounts for 25% of Q. Finally, isotope C has an atomic mass of
41 amu and a natural abundance of 15%. What is the atomic weight of element Q?
Solution: 0.60(40 amu) + 0.25(44 amu) + 0.15(41 amu) = 24.00 amu + 11.00 amu + 6.15 amu =
41.15 amu
The atomic weight of element Q is 41.15 g/mol.
(Incidentally, if you have studied physics, you may be aware of the distinction between mass and
weight. As you can see, chemists are a bit sloppier on this matter.)