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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.

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2021

Electronegativity: A Three-Part Wave

René Vernon points out that although there is a general trend in increasing electnegativity from Cs to F, there is actually an s-curve in the data.

Electronegativity across groups 1 to 18 appears to a show a three-part wave-like pattern.

There is a rise from group 1 to group 6, followed by a fall at group 7. I guess for group 7 that the EN for Mn is based on +2 and in this state Mn has five 3d electrons. The EN for Tc and Re are presumably based on +7, in which they notionally have underlying [Kr] and [Xe] cores.

There is rise from 7 to 8 (why?); a mesa from 8 to 11 (why?) that includes the PGM; and a fall at group 12. The fall may be influenced by group 12 having a full d shell; ditto group 13.

There is a rise from 13 to 18. Whereas in group 13 there is ionic chemistry in the form of the cations of Al to Tl this is not the case for C, Si, and Ge in group 14. Sn is reluctant to form a cation expect at pH < 1, and there is no Pb4+ cation.

The R2 value of 0.9739 is a best fit value for a second order polynomial. R2 for a straight line is 0.786


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