The atomic weight of a newly discovered element is 10.600 amu. It has two naturally occurring isotopes. One has a mass of 10.000 amu and a natural abundance of 70.000%. What is the isotopic mass of the other isotope?

1 Answer
Nov 7, 2015


The atomic mass is the weighted average of the individual isotopes. You have 1 equation, and 1 unknown.


So, #10.600 (mass# #units) = 70%xx10.000 + 30%xxM_2;# where #M_2# is the isoptopic mass of the other isotope.

So solve for #M_2#! A priori would you expect #M_2# to be larger or smaller than the mass of of the other isotope; why?