The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows periodic trends. The seven rows of the table, called …
Glenn T. Seaborg, in 1945, suggested a new periodic table showing the actinides as belonging to a second f-block series.
Image: Medeleeff by repin
Image: D. Mendeleev's Periodic table from his book
Image: Periodic table 14Ce Th form Group 3 = Sc Y La Ac