previous home next

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:

Text search:       

Periodic Table formulations from the year 1945:

1945   Segrè Chart of Elements & Isotopes
1945   Seaborg's Periodic Table of 1945
1945   Krafft's Periodic Table (1945)
1945   Discovery of Promethium


Segrè Chart of Elements & Isotopes

The Segrè chart of elements and isotopes arranges atomic nuclei by numbers or protons and numbers of neutrons and is a table of nuclides. There are various ways the axes can be arranged. From elsewhere in this chemogenesis web book:

And from Wikipedia:

Top of Page


Seaborg's Periodic Table of 1945

From his Priestly Medal Address, The Periodic Table: Tortuous Path to Man-Made Elements printed in C&EN April 16, 1979 and reprinted in Modern Alchemy: Selected Papers of Glenn T. Seaborg (1994), page 181.

Seaborg describes how "the theory was advanced that [the] new elements heavier than than actinium might constitute a second series similar to the series of 'rare-earth' or 'lanthanide' elements":

Top of Page


Krafft's Periodic Table (1945)

From Ether and Matter, p. 86, Carl Frederick Krafft:

Thanks to Edmond Maurice Peyroux for the tip!

Top of Page


Discovery of Promethium


Promethium, atomic number 61, has a mass of 145 au.

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

Promethium was first observed or predicted in 1942 by S. Wu, E.G. Segrè and H. Bethe and first isolated in 1945 by Charles D. Coryell, Jacob A. Marinsky, Lawrence E. Glendenin, and Harold G. Richter.

Top of Page

previous home next
What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

Queries, Suggestions, Bugs, Errors, Typos...

If you have any:

Suggestions for links
Bug, typo or grammatical error reports about this page,

please contact Mark R. Leach, the author, using

This free, open access web book is an ongoing project and your input is appreciated.