Originally posted by Chakotay
reply to post by Blue Shift
Some 3-d models are
These 3-d models are deep.
The three-dimensional designs are revolutionary but there are other, more conventional options that are both roughly quadrangular and two-dimensional
like the original Russian one, which nearly came out looking like a spiral. Mendeleiev tried and failed to design one with a spiral shape and now
Philip Stewart (Oxford U.) suggests going back to that.
So, it turns out that many people DO think the standard table is mistaken, but as concerns the proper distribution of the elements, not their basic
individual data in any essential way. It is claimed that 2-D tables are still being used simply because they're easier to render on paper (textbooks)
The one we're all acquainted with has several inconsistencies. The first period (row) is anomalous. It's the only one that stands alone. It breaks
the pattern by having no additional period with the same number of elements (two: H and He). The next two periods or rows both have eight, the next
two both have 16 and the next two 32. This oddity is eliminated in Charles Janet's tidy design that is "laddered" from left to right, and which also
shows more adequately the order in which the electron shells fill up. It was developed in the Twenties and has been brought back by Gary Katz.
Besides, the standard one places helium with the inert (noble) gases (group or column 18, last one on the right). Some say that it should be in group
2, at the top of this column, whose elements all have two valence electrons, like helium.
Thirdly, its groups 3 and 13 are separated by nine columns, yet they both have elements with valence number 3. In the 3-D Dufour model, the
ElemenTree, that looks like a conifer (pine tree) and was developed in 1990, all of these elements are grouped together. It stresses the chemical
similarities that the standard model doesn't show.
All these improvements were discussed by Eric R. Scerri in the "Scientific American" magazine in 2008, including one of his own. The problem is that
there is no agreement concerning the best design. Most chemists tend to feel that no design is better than the rest but some philosophers of science
edit on 1-1-2011 by escapevelocity because: In the third paragraph it had to be "no additional period", not "no additional group".