Final answer:
The average atomic mass of bromine is 79.9166 amu.
Step-by-step explanation:
The average atomic mass of an element is calculated by taking into account the masses and abundances of its isotopes. For bromine, the two naturally occurring isotopes are Br-79 and Br-81.
First, we need to convert the abundances of the isotopes into mass fractions. The abundance of Br-79 is 50.69%, which can be converted to a mass fraction of 0.5069. The abundance of Br-81 is 49.31%, which can be converted to a mass fraction of 0.4931.
Next, we multiply the mass fractions by the mass of each isotope to get the weighted masses. The mass of Br-79 is 78.9183 amu and the mass of Br-81 is 80.9163 amu. The weighted mass of Br-79 is 0.5069 * 78.9183 = 39.9924 amu and the weighted mass of Br-81 is 0.4931 * 80.9163 = 39.9242 amu.
Finally, we add together the weighted masses to obtain the average atomic mass of bromine. The average atomic mass of bromine is 39.9924 amu + 39.9242 amu = 79.9166 amu.