Question

On average, how many neutrons does one atom of bromine(Br) have?

Atomic # - 35
Atomic mass - 79.9

A. 35
B. 44.90
C. 45
D. 79.90

Answer 1

The average atomic mass of bromine is 79.90 amu, so on average, one atom of bromine has approximately 79.90 neutrons.

Step-by-step explanation:

The atomic mass of an element is the weighted average of the masses of its isotopes. Bromine (Br) has two isotopes: 79Br and 81Br. The mass of 79Br is 78.9183 amu, and its abundance is 50.69%. The mass of 81Br is 80.9163 amu, and its abundance is 49.31%. To calculate the average atomic mass of bromine, we multiply the mass of each isotope by its abundance, then add the results together:

(78.9183 amu * 0.5069) + (80.9163 amu * 0.4931) = 79.90 amu

Therefore, on average, one atom of bromine has approximately 79.90 neutrons.