What is the symbol for an atom containing 20 protons and 22 neutrons?
Got a Periodic Table? Of course you have....
A quick glance tells me that for
And this particular nucleus contains an additional 22 massive particles of ZERO charge....i.e. 22 neutrons. Interactions between protons and neutrons somehow result in the strong nuclear force, an attractive force at nuclear ranges that is strong enuff to overcome the electrostatic force of repulsion between the nuclear protons.... And so we got the isotope