Elementary particles are the smallest known particles in the universe and are the building blocks of all matter. Neutrinos, mesons, bosons, electrons, neutrons, muons, hadrons, leptons, atoms, quarks, and ions are all examples of elementary particles. Neutrinos are subatomic particles with no electric charge and very little mass. Mesons are particles composed of one QUARK and one antiquark. Bosons are particles that have an integer spin and obey Bose-Einstein statistics. Electrons are negatively charged particles that orbit the nucleus of an ATOM. Neutrons are electrically neutral particles found in the nucleus of an ATOM. Muons are unstable subatomic particles with a negative electric charge. Hadrons are particles composed of quarks and gluons. Leptons are particles that do not interact through the strong nuclear force. Atoms are the smallest particle of an element that can exist and still retain its chemical properties. Quarks are fundamental particles that make up protons and neutrons. Ions are atoms or molecules that have a net electric charge due to the loss or gain of electrons.