The INTERNET Database of Periodic Tables
There are hundreds 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.
Newlands Revisited – Poster
At the beginning of last year (Meyers, 2009), a IUPAC editorial offered "something old, something new, something borrowed and something blue".
Marks and Marks 2010 (M&M) preserves the old subgroups (Newlands' columns) that were a feature of all short forms, although M&M would then have been described as a 'medium form' (14 groups) in contrast to Mendeleyev's 'short form' (8 groups) or Werner's 'long form' (32 groups). M&M naturally continues the grouping of the lanthanoids/actinoids whose initial four groups were also included in 'short form' tables.
The logic of the arrangement of the s-elements is a new feature. It recognizes the chemical subgroups of hydrogen, viz. the alkali metals and the halogens, and of helium, viz. the alkaline earth metals and the inert gases. It is interesting to note that subgroups differ chemically from each other inversely as the azimuth, i.e. Li:F > Ca:Zn > La:Lu.
The whole idea is, of course, borrowed from Newlands. The group numbers are borrowed from valency but also from electronic structure in that the number of s, p, d, or f subgroups corresponds to the Pauli maximum for each. Finally, the mnemonic reflects that most elementary introduction to chemistry: alkalis turn Litmus blue.
From this start, the p-bloc is red, the transition elements yellow and the "rare earth" elements green, as argued in the M&M paper. The numbering of groups I - XIV is unambiguous, it is less than IUPAC's arbitrary 18 groups, it preserves subgroups and satisfactorily accommodates hydrogen and the lanthanoids/actinoids.
As required by Leigh (2009), this table is clear, simple and brief.
GJ Leigh "Periodic Tables and IUPAC" Chemistry International 2009, 31: 4-6. EG Marks & JA Marks "Newlands Revisited: a periodic table for chemists" Foundations of Chemistry 2010, 12: 85-93. F Meyers "From the Editor" Chemistry International 2009, 31:1-2.
© Mark R. Leach 1999-
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