The periodic table is a fundamental tool in the study of chemistry, which allows the elements to be classified and organized according to their physical and chemical properties. Throughout history, the periodic table has evolved thanks to the contributions of scientists and chemists who have discovered new elements and have refined its organization.
In this timeline of the periodic table, you will be able to discover the most important milestones in its development, from the first classifications of the elements to the inclusion of new synthetic elements in the 21st century.
Periodic Table Timeline
1789: French chemist Antoine Lavoisier classifies the known elements into groups of oxides, acids, metals, and nonmetals.
1817: German chemist Johann Döbereiner proposes the Law of Triads, which states that elements can be grouped into triads in which the middle element has properties intermediate between the other two.
1829: German chemist Johann Wolfgang Döbereiner proposes the Law of Octaves, which states that chemical elements can be grouped into groups of eight, in which the elements have similar properties and repeat periodically.
1864: British chemist John Newlands proposes the Improved Law of Octaves, showing the periodicity of elements in groups of eight.
1869: Russian chemist Dimitri Mendeleyev publishes the first version of his periodic table, organizing the elements by atomic weight and showing the periodicity of chemical properties.
1871: English chemist Lothar Meyer publishes a version of the periodic table similar to Mendeleev's, also organizing the elements by atomic weight.
1913: British chemist Henry Moseley establishes that the atomic number of an element is the property that determines its position in the periodic table.
1914: German physicist Julius Lothar Meyer publishes a revised version of the periodic table, in which he organizes the elements by their atomic number instead of atomic weight.
1940: Glenn T. Seaborg and his colleagues discover several synthetic elements and expand the periodic table to include them.
1951: British physicist Edwin McMillan and his colleague Glenn T. Seaborg discover the first transuranium element, neptunium.
1955: Glenn T. Seaborg and his colleagues propose a revision of the periodic table to include the transuranium elements.
1969: British chemist Neil Bartlett discovers the first noble gas compound, furthering the understanding of noble gases and their position on the periodic table.
2016: The periodic table is expanded with the inclusion of four new elements, completing the seventh period of the table.