The periodic table has been stamped into the minds of countless
generations of schoolchildren. Immediately recognised and universally
adopted, it has long since achieved iconic status.
So why change it? According to Mohd Abubakr from Microsoft
Research in Hyderabad, the table can be improved by arranging it in
circular form. He says this gives a sense of the relative size of
atoms–the closer to the centre, the smaller they are–something that is missing from the current form of the table. It preserves the periods and groups that make Mendeleev’s table so useful. And by placing hydrogen and
helium near the centre, Abubakr says this solves the problem of
whether to put hydrogen with the halogens or alkali metals and of
whether to put helium in the 2nd group or with the inert gases.
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That’s worthy but flawed. Unfortunately, Abubakr’s arrangement
means that the table can only be read by rotating it. That’s tricky with
a textbook and impossible with most computer screens.
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The great utility of Mendeleev’s arrangements was its predictive
power: the gaps in his table allowed him to predict the properties of undiscovered elements. It’s worth preserving in its current form for that reason alone.
However, there’s another relatively new way of arranging the elements developed by Maurice
Kibler at Institut de Physique Nucleaire de Lyon in France that may have new predictive power.
Kibler says the symmetries of the periodic table can be captured by
a group theory, specifically the composition of the special orthogonal group in 4 + 2 dimensions
with the special unitary group of degree 2 (ie SO (4,2) x
SU(2)).
That gives a layout as follows:
Kibler’s approach is akin to the way particle physicists classify
particles by their symmetry properties such as flavor and color. That has
been hugely useful in predicting the existence of new particles. Can the power of this group theoretical approach have the same impact on chemistry?
The problem for Kibler (and anybody else attempting to redraw the table of elements) is that we seem to have already found all the
stable elements and predicted the existence of other superheavy ones.
The question is whether Kibler’s approach has any predictive power
beyond that. Maybe but the jury (and Kibler himself) is still out on this one.
Refs:
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arxiv.org/abs/0910.0273: An Alternate Graphical Representation of Periodic table of Chemical Elements
