Is the Periodic Table of Elements Wrong?

Originally posted by Chakotay
reply to post by Blue Shift

 

Some 3-d models are here.

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) and blackboards.

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 disagree.

reply to post by SonOfTheLawOfOne

S and F for you sir!

Oh boy this is a seismic change. But will it affect high school chemistry? Will we still be able to predict chemical reactions between elements. Hydrogen and Carbon are significant elements. I have not been in high school since the 70s. But chem was always one of my favorites so forgive me if I make a few elementary mistakes in my reasoning (lol).

This isn't that big a deal.

The atomic mass stated in the periodic table has always been the mean atomic mass (also expressed as the weight in grams of one mole of the element). The mean atomic mass is based on the relative weights of the naturally occurring isotopes of the element at the surface of the earth.

For instance, a random collection of of one mole (6.022 * 10^23 atoms) of carbon atoms will tend to be 98.93% Carbon-12 and 1.07% Carbon-13.

Carbon-12 has an atomic mass of 12. 98.93% of 12 is 11.8716.
Carbon-13 has an atomic mass of 13.00335. 1.07% of 13.00335 is 0.139135845.

Add 11.8716 and 0.139135845 and you get 12.011, which is the atomic mass of Carbon as expressed in the periodic table.

All this update has done is refined the percentages of the naturally occurring isotopes of these elements, as our understanding of the precise percentages has become more accurate.