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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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1950

McCutchon's Simplified Periodic Classification of the Elements

McCutchon KB, A simplified periodic classification of the elements, Journal of Chemical Education, vol. 27, no. 1, pp. 17–19 (1950)

This 3-dimensional table has two double-sided flaps attached. The top flap is the f bock. Under that is the d block.

The superscripts denote the number of d electrons an element has. Thus, La1 is shown as being an f1 element. But it has a 1 superscript, meaning that the f electron count is reduced by 1 and the d electron count is 1.

René Vernon writes:

"On group 3, McCutchon cryptically says: The proposed arrangement brings out certain known facts about the tertiary elements which are rarely shown by other arrangements. For example, it suggests, correctly, that the resemblance between yttrium and lutecium is greater than that between yttrium and lanthanum. It classifies lanthanum but not lutecium as a rare earth, in accordance with their chemical properties (which also contradict spectrographic evidence at this point). It also demonstrates the tetravalence of both cerium and thorium, and that thorium and protactinium show a resemblance in chemical properties to zirconium and niobium, as well as to hafnium and tantalum."

I say "cryptically" because McCutchon presents no further evidence in support of his assertion that the resemblance between Y and Lu is greater than between Y and La. He may have had in mind the fact that Lu is more often found in ores of Y than is the case for La... and I don't understand his reference to spectrographic evidence.





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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –


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