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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 1100 Period Tables in the database:

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2004

Mass Anomaly Periodic Table

Pairs of atoms where atomic mass does not follow atomic number.

 
Co
=
58.933  
Ni
=
58.69
 
Ar
=
39.948  
K
=
39.098
 
Te
=
127.60  
I
=
126.90

Nature's little quirk – due to the intricacies of nuclear chemistry and isotopic abundance – caused no end of difficulties to the developers of the periodic table in the mid-nineteenth century. Scientists could determine atomic mass, but knew nothing of protons or atomic numbers.

The tellurium-iodine anomaly was a particular problem.

By Mark Leach

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –


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