History of the periodic table the Periodic Law for the chemical elements". He contributed the word 'periodic' in chemistry. The Russian chemist Dmitri Mendeleev was the first scientist to make a periodic table similar to the one used today. Mendeleev arranged the elements by atomic mass, corresponding to relative molar mass. It is sometimes said that he played 'chemical solitaire' on long train journeys, using cards with various facts about the known elements. On March 6, 1869, Mendeleev gave a formal presentation, "The Dependence Between the Properties of the Atomic Weights of the Elements", to the Russian Chemical Society. In 1869, the table was published
Alternative periodic tables extended periodic table, suggested by Glenn T. Seaborg in 1969, yet unknown elements are included up to atomic number 218. Theoretical periods above regular period 7 are added. In the research field of superatoms, clusters of atoms have properties of single atoms of another element. It is suggested to extend the periodic table with a second layer to be occupied with these cluster compounds. The latest addition to this multi-story table is the aluminium cluster ion , which behaves like a multivalent germanium atom. Alternative periodic tables Alternative periodic tables are tabulations of chemical elements differing significantly in their organization