Periodic Table |
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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 hold information on periodic tables, the discovery of the elements and elucidation of atomic weights (and more).
Periodic Tables from the year 2026:
| 2026 | The Approximate Chemical Formula of the (Observable) Universe |
| 2026 | Pairs and Squares Periodic Table |
| Year: 2026 | PT id = 1347, Type = misc |
The Approximate Chemical Formula of the (Observable) Universe
From xkcd, The Approximate Chemical Formula of the (Observable) Universe:
Thanks to Marcus for the tip!
| Year: 2026 | PT id = 1365, Type = formulation |
Pairs and Squares Periodic Table
"Pairs and Squares" Periodic Table by Leonid A. Levin of Boston University
Leonid writes:
"All the tables [in the PT Database] share a common problem: their irregularity exceeds by far their periodicity.
"In my youth I was greatly bothered by this. Yet, taking advantage of a few patterns in atomic orbitals allows a complete elimination of all irregularities, putting all periods in a perfect pattern.This perfectly regular rendition would be much more comfortable, especially at one's first high school exposure to this Science symbol.I am attaching such "Pairs and Squares" rendition with a brief explanation."
"Read more in the full 'Pairs and Squares' paper, here."

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| What is the Periodic Table Showing? | Periodicity |
© Mark R. Leach Ph.D. 1999 –
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