Particles can be sorted into two main groups according to whether or not they feel the strong nuclear force.Hadrons are particles (and antiparticles) that are affected by the strong nuclear force. Examples are the proton and the neutron. Hadrons are not fundamental: they are made of quarks. Hadrons may also feel the weak nuclear force and, if they are charged, the electromagnetic force. There are two families of hadrons, called baryons and mesons.Leptons are particles (and antiparticles) that are not affected by the strong nuclear force. They interact through the weak nuclear force and, if charged, the electromagnetic force (and gravity, like all particles with mass). Examples are the electron and the neutrino. Leptons are fundamental particles.Summary:• hadron: feels the strong force; made of quarks; for example p, n
• lepton: does not feel the strong force; fundamental; for example e−, νThe neutrino is a lepton with zero charge and a very small mass. Because it is neutral and does not feel the strong force, it interacts only through the weak force (and gravity), so it passes through matter extremely easily. Billions pass through your body every second.This classification helps explain the atom. Protons and neutrons are hadrons, so the strong force holds them together in the nucleus. Electrons are leptons, so the strong force does not act on them; they are held in the atom by the electromagnetic force only.The proton is the only stable hadron. A free neutron decays (through the weak force) with a half-life of about 10 minutes.
• lepton: does not feel the strong force; fundamental; for example e−, νThe neutrino is a lepton with zero charge and a very small mass. Because it is neutral and does not feel the strong force, it interacts only through the weak force (and gravity), so it passes through matter extremely easily. Billions pass through your body every second.This classification helps explain the atom. Protons and neutrons are hadrons, so the strong force holds them together in the nucleus. Electrons are leptons, so the strong force does not act on them; they are held in the atom by the electromagnetic force only.The proton is the only stable hadron. A free neutron decays (through the weak force) with a half-life of about 10 minutes.