* Protons: Positively charged particles that determine the element of the atom. The number of protons is called the atomic number.

* Neutrons: Neutrally charged particles that contribute to the atom's mass but not its charge. The number of protons and neutrons together determine the atom's mass number.

While not always present, some atoms also have isotopes which are atoms of the same element that have different numbers of neutrons.

Let me know if you want to learn more about any of these!