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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 1100 Period Tables in the database:

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Allahyari & Oganov: Mendeleev Numbers & Organising Chemical Space

This formulation may not look like a periodic table, but look again.

Zahed Allahyari & Artem R. Oganov, Nonempirical Definition of the Mendeleev Numbers: Organizing the Chemical Space, J. Phys. Chem. C 2020, 124, 43, 23867–23878, A preprint version of the paper is available on the arxiv preprint server.


Organizing a chemical space so that elements with similar properties would take neighboring places in a sequence can help to predict new materials. In this paper, we propose a universal method of generating such a one-dimensional sequence of elements, i.e. at arbitrary pressure, which could be used to create a well-structured chemical space of materials and facilitate the prediction of new materials.

This work clarifies the physical meaning of Mendeleev numbers, which was earlier tabulated by Pettifor. We compare our proposed sequence of elements with alternative sequences formed by different Mendeleev numbers using the data for hardness, magnetization, enthalpy of formation, and atomization energy. For an unbiased evaluation of the MNs, we compare clustering rates obtained with each system of MNs.

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What is the Periodic Table Showing? Periodicity

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