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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: 

  Text Search:       

Year:  2022 PT id = 1234

Kudan's Periodic Law (Helix Form)

From Pavel V. Kudan, a specialist in mass-spectrometry and identification of compounds, who suggests a helical variant of the Periodic table. The graphical representation illustrates the Periodic Law and the following features of the Kudan’s periodic system:

    1. Four element periods (1, 2, 3, 4)
    2. Two element half periods (-,+)
    3. Twenty one element subgroups octet rule compatible (1a-8a, 2b-8b, 3c-8c)
    4. Small energy barriers between S and F, F and D, D and P elements (gray segments)
    5. Large energy barriers between P and S elements (black segments)
    6. Large energy barrier between He and Li (black segments)

(See also Kudan’s Left-Step Periodic Table)

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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