* Protons: The number of protons defines the element. Chlorine always has 17 protons.
* Electrons: In a neutral atom, the number of electrons is equal to the number of protons. So, chlorine-37 has 17 electrons.
* Neutrons: The mass number (37 in this case) represents the total number of protons and neutrons.
* To find the number of neutrons, subtract the number of protons from the mass number: 37 - 17 = 20 neutrons.
Therefore, a chlorine-37 atom has:
* 17 protons
* 17 electrons
* 20 neutrons
