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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:  1937 PT id = 823

Discovery of Technetium


Technetium, atomic number 43, has a mass of 98 au.

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

Technetium was first isolated in 1937 by C. Perrier and E. Segrè. The element had been predicted by Mendeleev in 1871 as eka-manganese.

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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