How many neutrons are in the nucleus of a atom?

Answer 1

Atomic nuclei are composed of protons and neutrons. The atomic number of an element shows the number of protons in a nucleus of an atom of that element, while the Atomic Mass shows the average number of nucleons (either a proton or a neutron) in nuclei of that element. There can be an average because, unlike proton number, neutron number can vary from isotope to isotope. For example, carbon can have 6 or 7 neutrons and still be stable, but it always has to have 6 protons, or else it'd be a different element.

Because atomic mass is equal to the number of protons and neutrons, one can find the number of neutrons by subtracting the number of protons from the total number of nucleons in a given isotope. To do this, subtract the atomic number from the atomic mass.