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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:  1913 PT id = 871

Discovery of Protactinium


Protactinium, atomic number 91, has a mass of 231.036 au.

Radioactive element: Pa is only found in tiny amounts in nature. Most samples are synthetic.

Protactinium was first observed or predicted in 1913 by O. H. Göhring and K. Fajans and first isolated in 1927 by A. von Grosse.

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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