Particles and antiparticles

It is important to avoid turning this entire topic into ‘stamp collecting’. The underlying themes to develop here are that discoveries in nuclear physics, accelerating during the middle of the twentieth century, resulted in a need to classify the particles discovered. The key to this classification was the application of conservation laws, some of quantities already well established (charge, baryon number), some modified from earlier versions (mass/energy) and some new (lepton number) or even bizarre (strangeness is the one met here, but there are also parity, isospin and hypercharge). The other aspects developed are: antiparticles, the explanation of particle interactions in terms of exchange particles (vector bosons), and the development of the standard model of three generations of quarks and leptons to explain and simplify the ‘particle zoo.’