#Elements table series#
Methods for displaying the periodic table Standard periodic table Group →Ĭhemical Series of the Periodic Table Alkali metals Seaborg identified the transuranic lanthanides and the actinides, which may be placed within the table, or below (see the different possible arrangements below).
Chemists were able to qualitatively explain the behavior of the elements, and to predict the existence of yet undiscovered ones. Mendeleev's and Moseley's development of the periodic table was one of the greatest achievements in modern chemistry. Today's table uses this ordering by atomic number (number of protons). In 1913, Henry Moseley rearranged the table according to atomic number to improve the observed periodicity in the chemical properties across the table. The modern table is based on this understanding of the electronic structures. Mendeleev was later vindicated by the discovery of the electronic structure of the elements in the late nineteenth century and early twentieth century. He also corrected mistakes in the values of several atomic masses, and predicted the existence and properties of a few new elements in the empty cells of his table. However, Mendeleev plotted a few elements out of strict mass sequence in order to make a better match to the properties of their neighbors in the table. Finally, in 1869, the German Julius Lothar Meyer and the Russian chemistry professor Dmitri Ivanovich Mendeleev almost simultaneously developed the first periodic table, arranging the elements by mass. This was followed by the English chemist John Newlands, who noticed in 1865 that the elements of similar type recurred at intervals of eight, which he likened to the octaves of music, though his law of octaves was ridiculed by his contemporaries. The first to recognize these regularities was the German chemist Johann Wolfgang Döbereiner who, in 1829, noticed a number of triads of similar elements: If the elements are ordered by atomic mass then a certain periodicity, or regular repetition, of physical and chemical properties can be observed.
The original table was created without a knowledge of the inner structure of atoms, but rather by correlating physical and chemical properties of the elements with atomic mass. History Main article: History of the periodic table
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