Periodic Law

In chemistry, the Periodic Law states that if the chemical elements are listed in order of increasing atomic number, many of their properties go through cyclical changes, with elements of similar properties recurring at intervals. For example, after arranging elements in their increasing atomic numbers, many of the physical and chemical properties of Lithium are recurred into Sodium such as its vigorous reactivity with water, which again recurs in the next cycle starting with Potassium.

This principle was discovered after number of investigations done by scientists in nineteenth century such as Lothar Meyer and Dmitri Mendeleev. Initially, no theoretical explanation for the Periodic Law was available and it was used only as an empirical principle. But, with the development of electronic theory of atomic structure, it became possible to understand the theoretical basis for the Periodic Law. From the modern periodic table, it is evident that the periodic recurrence of elements with similar physical and chemical properties, when the elements are listed in order of increasing atomic number, results directly from the periodic recurrence of similar electronic configurations in the outer shells of respective atoms.

Discovery of Periodic Law constitutes one of the most singularly important events in the history of chemical science. Almost every chemist makes extensive and continued use of Periodic Law. Periodic Law also led to the development of the periodic table, which are widely used nowadays.

See also

• History of the periodic table