Decades ago particle physicists were observing new particles in the laboratory faster than they could predict or explain them. When they eventually did explain new particles with the quark model, these scientists still relied upon the laws of conservation of charge and conservation of energy as part of the new theory.
When a lone particle flies apart into two or more new particles, the event is called a decay.
Conservation of charge tells us to expect the net charge of all particles produced in a decay should equal the total charge on the original particle. Conservation of energy implies that the total mass of the resulting particles should not be greater than the mass of the original particle.
On the following Web page, you will see symbols for particles. By clicking on any one symbol, you can observe a typical decay of that particle. At first, these decays may seem random in the combinations they show. However, there is an underlying pattern.
If you want to see a list of particles along with their masses and their charges, just go to the particle table. If you would like to know the definitions of some unfamiliar terms, try the glossary at Boston University.