* Protons: Positively charged particles. The number of protons in an atom determines what element it is. For example, all carbon atoms have 6 protons.
* Neutrons: Neutrally charged particles. They contribute to the atom's mass but don't affect its charge. The number of neutrons can vary in an atom, leading to different isotopes of the same element.
Together, protons and neutrons make up almost the entire mass of an atom, and they are tightly bound together in the nucleus. The nucleus is incredibly dense, containing most of the atom's mass in a very small space.
