Question: how many protons neutrons and electrons are there in an atom of chlorine-39?
Answer: An atom of chlorine-35 contains 18 neutrons (17 protons + 18 neutrons = 35 particles in the nucleus) while an atom of chlorine-37 contains 20 neutrons (17 protons + 20 neutrons = 37 particles in the nucleus). Adding or removing a neutron from an atom's nucleus creates isotopes of a particular element.