Hello!
To answer your question lets first establish the different parts of the atom that can be affected.
Protons: Subatomic particle in the nucleus with a positive charge
Neutrons: Subatomic particle, around the same mass as the proton, with a neutral charge.
Electrons: Subatomic particle outside the nucleus with a negative charge
This particular question relates to isotopes in our elements. It's important to note that the most common/stable forms of an element are what correspond to the periodic table however they can differ in the total particles in the nucleus.
The reason they differ is because the number of neutrons (either added or removed from the nucelus) affect the isotope! Protons and electrons stay the same however as once those are removed they represent another element.
I hope this answers your question. If you need anymore clarification please ask!
