The Basic Particles

What are the basic particles of matter?

Imagine six different kinds of tiny particles called quarks, and six more called leptons. Now imagine each of them having an "antimatter" twin, identical in mass, but diametrically opposite in certain properties, such as electric charge.

These are all you need to build the hundreds of subatomic particles of matter that we know of -- these, plus a little energy to bind them together in certain groups.

Some of the "rules" for building matter are:

1. Leptons can exist alone, but quarks are found only in certain groupings, called baryons and mesons.
2. With quarks, leptons, or their composites, the heavier particles are all unstable. When composites of heavy quarks are formed in cosmic reactions or in physics experiments, they break down rapidly Ñ in physics terminology, they "decay" -- ultimately to electrons and neutrinos or to stable quark composites (containing up and down quarks).
3. When these basic particles decay or interact, mass frequently turns into energy and vice versa, according to Einstein's famous equation E=mc2.