Bromine (Br) is made up of two isotopes, Br-79 (78.9183 amu) and Br- 81 (80.9163 amu).

Given bromine’s atomic weight of 79.904 amu, what is the percent abundance of each isotope?

77. Bromine has two naturally occurring isotopes (Br-79 and Br-81) and has an atomic mass of 79.904 amu. The mass of Br-81 is 80.9163 amu, and its natural abundance is 49.31%. Calculate the mass and natural abundance of Br-79.

Bromine has two occurring isotopes: 79Br with atomic mass 78.9183 and 81Br with atomic mass 80.9163. Without using a calculator, what would you estimate the % abundance of Br-79 to be?

76. An element has four naturally occurring isotopes with the masses and natural abundances given here. Find the atomic mass of the element and identify it. Isotope Mass (amu) 135.90714 137.90599 Abundance (%) 0.19 0.25 2 88.43 139.90543 141.90924 11.13 +