Periodic Table of the Elements

The periodic table of the chemical elements is the single most important concept in chemistry. It has evolved as a classification scheme through a number of well-defined stages. It has provided, at all stages, a detailed summary of all available knowledge pertaining to the physical and chemical properties of the elements and their compounds. More importantly, it reflects the current state of theoretical chemistry at any time. The classification was based at different times on the appearance of substances, chemical affinity, atomic weight, atomic number and the electronic configuration of atoms. The parallel development of a periodic table is traced in the following historical review, based to a large extent on the work of Partington [31].