Particle Names



A particles name will sometimes include the atomic mass number of the particle.

For example, chlorine-37 is a chlorine atom that has an atomic mass number of 37, meaning that it has a total of 37 protons and neutrons in its nucleus.

Since the atomic number for chlorine is 17, any chlorine atom or ion always has 17 protons.  Therefore, a chlorine-37 atom has 20 neutrons, because 37 minus 17 equals 20.