Internet Database of Periodic Tables
There are thousands of periodic tables in web space, but there is only one comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Dr Mark R Leach.
Use the buttons below to select from the 1000+ Periodic Tables in the database:
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.
© Mark R. Leach 1999-
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