The two isotopes of antimony have masses 120.90 and 122.90, with a relative abundance of 57.25% and 42.75% respectively. Using these figures, distinguish clearly between atomic mass, isotopic mass, and mass number.
The Attempt at a Solution
I think atomic mass is the relative isotopic abundance which in our case would be
(0.5725)(120.90) + (.4275)(122.90) = 121.755
Would isotopic mass be simply 120.90 and 122.90?
Would mass number be the same as the atomic mass?
Some how I think I am wrong concerning the last two.