A BRIEF HISTORY OF THE DEVELOPMENT OF PERIODIC TABLE

Johann Dobereiner noticed that the atomic weight of strontium fell midway between the weights of calcium and barium, elements possessing similar chemical properties

Johann Dobereiner proposed that nature contained triads of elements the middle element had properties that were an average of the other two members when ordered by the atomic weight (the Law of Triads)

A number of scientists including; Jean Baptiste Dumas, Leopold Gmelin, Ernst Lenssen, Max von Pettenkofer, and J.P. Cooke, found that these types of chemical relationships extended beyond the triad. Unfortunately, research in this area was hampered by the fact that accurate values of were not always available.

French geologist, A.E.Beguyer de Chancourtois transcribed a list of the elements positioned on a cylinder in terms of increasing atomic weight. When the cylinder was constructed so that 16 mass units could be written on the cylinder per turn, closely related elements were lined up vertically. This led de Chancourtois to propose that "the properties of the elements are the properties of numbers." De Chancourtois was first to recognize that elemental properties reoccur every seven elements, and using this chart, he was able to predict the stoichiometry of several metallic oxides. Unfortunately, his chart included some ions and compounds in addition to elements.

John Newlands, an English chemist, wrote a paper which classified the 56 established elements into 11 groups based on similar physical properties, noting that many pairs of similar elements existed which differed by some multiple of eight in atomic weight.

Newlands published his version of the periodic table and proposed the Law of Octaves. This law stated that any given element will exhibit analogous behavior to the eighth element following it in the table.

Meyer's textbook included a rather abbreviated version of a periodic table used to classify the elements. This consisted of about half of the known elements listed in order of their atomic weight and demonstrated periodic valence chages as a function of atomic weight.

Meyer constructed an extended table which he gave to a colleague for evaluation.

Mendeleev's table became available to the scientific community via publication