Not too long ago, matter was thought to come in just a few garden variety elementary particles: electrons, protons, and neutrons.

Today a much greater richness in the number of elementary particles is appreciated [local].

The periodic table of Mendeleev was developed on the basis of the empirical properties of chemical elements. As it happens, other constraints have allowed physicists to write charts of fundamental particles. In a sense, these charts suggest properties that the fundamental particles might have, and allow the design of experiments to find those particles. In a superficial way, the search for subatomic particles has been driven by charts with gaps in a manner similar to the search for chemical elements.