Within a typical atom, there are three subatomic particles: protons, neutrons, and electrons. Other particles exist as well, such as alpha and beta particles. Though outdated the Bohr Model shows the three basic subatomic particles in a simple manner. Most of an atom's mass is in the nucleus, a small dense area at the center of every atom formed by nucleons. Nucleons are protons and neutrons. All of the positivity of an atom is contained in the nucleus, because the protons have a positive charge. Neutrons are neutral, meaning they have no charge. Electrons, which have a negative charge, are located outside of the nucleus.