As you can tell from the video above, atoms are made up of three main particles - protons, neutrons, and electrons. Protons and neutrons make up the center of the atom, or nucleus. Electrons then rotate around the nucleus in shells. The shells each can contain a certain number of electrons, and each shell has more electrons than the one before it. When the number of electrons equals the number of protons, that means that the atom has no charge. But, when the atom does have a charge, the number of protons and electrons are not equal.