<P> The importance of Newlands' analysis was eventually recognised by the Chemistry Society with a Gold Medal five years after they recognised Mendeleev's work . It was not until the following century, with Gilbert N. Lewis' valence bond theory (1916) and Irving Langmuir's octet theory of chemical bonding (1919), that the importance of the periodicity of eight would be accepted . The Royal Chemistry Society acknowledged Newlands' contribution to science in 2008, when they put a Blue Plaque on the house where he was born, which described him as the "discoverer of the Periodic Law for the chemical elements". </P> <P> He contributed the word' periodic' in chemistry . </P> <P> 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 in an obscure Russian journal and then republished in a German journal, Zeitschrift für Chemie . In it, Mendeleev stated that: </P> <Ol> <Li> The elements, if arranged according to their atomic mass, exhibit an apparent periodicity of properties . </Li> <Li> Elements which are similar as regards to their chemical properties have atomic weights which are either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly (e.g., K, Rb, Cs). </Li> <Li> The arrangement of the elements, or of groups of elements in the order of their atomic masses, corresponds to their so - called valencies, as well as, to some extent, to their distinctive chemical properties; as is apparent among other series in that of Li, Be, B, C, N, O, and F . </Li> <Li> The elements which are the most widely diffused have small atomic weights . </Li> <Li> The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body . </Li> <Li> We must expect the discovery of many yet unknown elements--for example, elements analogous to aluminium and silicon--whose atomic weight would be between 65 and 75 . </Li> <Li> The atomic weight of an element may sometimes be amended by a knowledge of those of its contiguous elements . Thus the atomic weight of tellurium must lie between 123 and 126, and cannot be 128 . </Li> <Li> Certain characteristic properties of elements can be foretold from their atomic masses . </Li> </Ol>

Who assigned atomic numbers to elements and arranged the periodic table that way