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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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Sneath's Dendtogram

Sneath, P., Numerical Classification of the Chemical Elements and Its Relation to the Periodic System. Foundations of Chemistry 2, 237–263 (2000).

Abstract: "A numerical classification was performed on 69 elements with 54 chemical and physicochemical properties... Only 15 properties were scorable for the noble gases, but despite the paucity of properties reflecting chemical reactivity, analysis of the 69 elements on these properties still showed the major features seen from the full set."

Sneath writes:

"The UPGMA tree shows three major clusters at the 70% similarity level:

1. Hydrogen, noble gases, reactive nonmetals and halogens.
2. A large cluster of less reactive metals and metalloids, with a few nonmetals.
3. A cluster of highly reactive metals.

These major clusters are almost consistent with the blocks based on electron shells. The first cluster belongs to the p-block plus hydrogen. The second belongs to the d-block together with a few p-block elements. The third consists of the s-block plus aluminum from the p-block.

Cluster 1: There are three subclusters. 1a. This contains hydrogen and the noble gases."

Thanks to René for the tip!

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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