Question

The atomic mass of an element is the weighted average of all of its isotopes. The percent abundance for the element boron is 19.9% boron-10 and 80.1% boron-11. Given the following atomic masses, determine the average atomic mass of the element boron.

Boron-10 has a mass of 10.0129370 amu
Boron-11 has a mass of 11.0093055 amu

Answer 1

.199 * 10.0129 + .801 * 11.009 = 1.0 * x
1.9926 + 8.818 = 10.81