As scientists' knowledge in quantum mechanics improved, it was clear that the periodic table needed to be re-organized. Dmitri Mendeleev provided an earlier draft of the periodic table that provided a foundation, but after the discoveries by Albert Einstein and Max Planck, Henry Moseley reorganized the periodic table by atomic mass.
Today, the periodic table lists elements in order of atomic number, and it categorizes the elements into groups according to their electron structure. This relationship between electron structure and the periodic table is a key aspect of chemistry. Chemists can analyze the periodic trends in order to predict the behavior of known elements and elements that have yet to be discovered.
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