To determine the number of neutrons in a bromine atom, follow these detailed steps:
1. Identify the atomic number of bromine, which is 35. The atomic number represents the number of protons in a bromine atom.
2. Identify the average atomic mass of bromine, which is 79.904. The atomic mass is approximately the total mass of the protons and neutrons in the atom.
3. To find the number of neutrons, subtract the atomic number from the atomic mass. Since the atomic mass is not typically a whole number, round the atomic mass to the nearest integer. In this case, round 79.904 to 80.
4. Perform the subtraction to find the number of neutrons:
[tex]\[
\text{Number of neutrons} = \text{Rounded atomic mass} - \text{Atomic number}
\][/tex]
[tex]\[
\text{Number of neutrons} = 80 - 35
\][/tex]
5. Calculate the result:
[tex]\[
\text{Number of neutrons} = 45
\][/tex]
Thus, bromine has 45 neutrons. The correct answer is 45.
