Video narration
Like adding positive and negative fractions, particle charges combine-but does every particle have smaller parts? The nucleus holds protons and neutrons; electrons occupy orbitals, not planet-like tracks. But the zoom doesn't continue the same way for every particle. An electron carries minus one and is elementary: no quark parts are known. Protons and neutrons contain three quarks, the building blocks: two up quarks and one down in a proton; one up and two down in a neutron. An up quark carries plus two-thirds of a charge; a down quark, minus one-third. For a proton: plus two-thirds, plus two-thirds, minus one-third-plus one. For a neutron: plus two-thirds, minus one-third, minus one-third-zero. Gluons carry the strong interaction that binds quarks together. So, can you zoom into every particle? No: protons and neutrons contain quarks; electrons, as far as we know, do not.