Question

A hypothetical element consists of 2 isotopes of masses 84.95 amu and 86.95 amu with abundance of 37.1% and 62.9% respectively. What is the average atomic mass?

Answer 1

The average atomic mass of the hypothetical element is the sum of the products of the isotopes and their percentage abundance. For this given,
                 atm = (84.95 amu)(0.371) + (86.95 amu)(0.629) 
                         = 86.208 amu
Thus, the average atomic mass of the element is 86.208 amu.