|To understand the implications of a scientific theory, it helps to imagine what the universe would be like if it were not true. If the Pauli exclusion principle were not valid, then the building up of the electronic structure of atoms as a succession of quantum states of increasing energy level would not occur. Occupied lower states would not exclude further occupancy. The periodic table of the elements would not exist, because the periodic table depends on the chemical differences produced by differences in ground state electron configuration among the elements.|
Although the periodic table was introduced prior to the advent of quantum mechanics, one of the most important insights one hopes students get early in college chemistry is how the organization of the periodic table corresponds directly to electron configuration.