Bromine has two naturally occurring isotopes, Br-79 and Br-81. The atomic mass of Br-79 is 78.9183 amu with a percent abundance of 50.69% and the atomic mass of Br-81 is 80.9163 amu. Calculate the atomic mass of bromine.
A)80.91 amu
B)78.92 amu
C)79.90 amu
D)80.92 amu
E)80.03 amu

Question

Quizplus · Accepted Answer

The atomic mass of bromine is calculated by taking the weighted average of its isotopes: (78.9183 amu * 0.5069) + (80.9163 amu * 0.4931) = 79.90 amu.

Bromine Has Two Naturally Occurring Isotopes, Br-79 and Br-81