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What is the Periodic Table Showing? Periodicity

The INTERNET Database of Periodic Tables

There are thousands of periodic tables in web space, but this is the only comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Mark R. Leach Ph.D. The database holds information on periodic tables, the discovery of the elements, the elucidation of atomic weights and the discovery of atomic structure (and much, much more).

   Use the drop menus or search box (below) to Select or Search the 1400 entries in the database: 

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Periodic Tables from the year 1895 :

1895   Retger's Periodic Table
1895   Thomsen's Systematic Arrangement of the Chemical Elements
1895   Helium, Discovery of


Year:  1895 PT id = 364, Type = formulation

Retger's Periodic Table

Periodic Table of Retgers with an intraperiodic accommodation of the rare earths. Retgers, J.W., 1895. Z. Phys. Chem. 16, 644:

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Year:  1895 PT id = 368, Type = formulation

Thomsen's Systematic Arrangement of the Chemical Elements

In 1895 the Danish thermochemist Hans Peter Jørgen Julius Thomsen proposed (Thomsen, J., 1895. Z. Anorg. Chem. 9, 190 & Chemical News, 72, 89–91, p. 90) a pyramidal/ladder representation.

Notice how this formulation identifies the electropositive & electronegative elements with respect to the periodic table, thirty years before Linus Pauling.

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Year:  1895 PT id = 782, Type = element

Discovery of Helium

He

Helium, atomic number 2, has a mass of 4.003 au.

Helium is a noble gas, and is the second most abundant element in the universe after hydrogen.

Helium was first observed or predicted in 1868 by P. Janssen and N. Lockyer from solar spectra, and first isolated in 1895 by W. Ramsay, T. Cleve, and N. Langlet.

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –


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