An atom of the isotope bromine-79 contains 35 protons, 44 neutrons, and 35 electrons.
To explain: The atomic number of bromine (Br) is 35, which means every bromine atom has 35 protons. Since it is a neutral atom, the number of electrons must also equal the number of protons, resulting in 35 electrons.
The mass number of bromine-79 is 79, which is the total number of protons and neutrons in the atom. To find the number of neutrons, you subtract the number of protons from the mass number:
Neutrons = Mass number – Protons
Neutrons = 79 – 35 = 44
Thus, the isotope bromine-79 has 35 protons, 44 neutrons, and 35 electrons.