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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 = 1280

Marks' Version of Mendeleyev's 1869 Formulation

John Marks, who provided the graphic, writes:

"I went back to Mendeleyev´s 1869 original and drew this (below) which demonstrates the Sommerfeldsche aufspaltung as occurring after completed s-subshells. No-one disputes the chemical phenomena of the octets formed by He/Ne, Li/Na, Be/Mg, B/Al, C/Si, N/P and O/S nor that H/F occurs at the beginning of these octets, however "irregular" H may appear.

"Chemical periodicity is clearly based on periods arising from sp3 hybridization and the aufspaltung appears to occur between the s and the p3. This gives rise to the positions of Sommerfeld's "Long" (with the d-elements) and "Very Long" (with the f-elements) periods."

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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