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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.

Use the drop menus below to search & select from the more than 1300 Period Tables in the database: 

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Year:  2023 PT id = 1279

Mendeleyev’s Periodic Table after Ramsay & Sommerfeld

John Marks, who provided the graphic, writes:

"This is the Ramsay-Sommerfeld PT and would seem to be the definitive PT, at least historically.

"Ramsay, a chemist, completed Mendeleyev's PT with the discovery of the inert gases in the 1890s and the position of hydrogen with the halogens by 1915.

"Sommerfeld, a physicist, generalized Bohr's atom in 1916 to yield the s-, p-, d- and f- electronic subshells that determine the layout of physicists' PTs, in particular their first "very short" period comprising H and He. Sommerfeld also explained the 'long periods', viz. the transition series ('A' subgroups) and the 'very long periods', viz. the rare earth series ('B' subgroups).

"In this chemistry/physics hybrid periodic table, the physicist Sommerfeld's first ('very short') "period" is subsumed under the chemist Ramsay's first two groups (-1 and 0) which are distinguished by colour: group -1 is white = 1s1p5, viz. H & the halogens; group 0 is black = 1s2p6, viz. He & the inert gases.

"Einstein's demonstration of atomic reality in 1905 (phenomena verified by Perrin in 1908) established the basic units of the paradigm of chemistry. Rutherford and Bohr (both physicists) went inside the atom, into the paradigm of physics.

"The PT thus straddles the borderland of the two paradigms of physics and chemistry and this has contributed significantly to the long debates on the form of the PT."

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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