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 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.
© Mark R. Leach 1999-
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