Tuesday, June 10, 2008

Spotting Gaps - The Periodic Table

No treatment of visualisation can get away without mentioning Mendeleev's periodic table of chemical elements (briefly summarised in the section Chemical Periodicity from the OpenLearn Unit The Molecular World, and seen in its historical context in Mendeleev's Lecture to the Royal Society on "The Periodic Law of the Chemical Elements").

The table lays out the chemical elements according to their physical and chemical properties, arranging the elements so that elements with similar properties appear in the same column of the table.

Read this Brief History of the Periodic table, or watch this explanation about the construction of The Periodic Table. Why is Mendeleev's periodic table of the chemical elements rightly seen as a prime example of the power of visualisation tools?

The structure of the table - 'groups' of elements arranged by column, 'periods' by row - manages to reflect something of the internal structure of the elements, and allows us to visualise 'similarity' (the number of free electrons) and 'progression' (increasing atomic weight) relations across the elements. At the time of its publication, the table also contained many gaps where Mendeleev expected to find elements with particular properties, but knew of no such elements. By virtue of their location in the table, these gaps essentially provided predictions about the physical and chemical properties of as yet (at the time) undiscovered elements. The table thus provided an "observer's guide" for the experimentalists seeking these new elements.

The Periodic Table of Chemical Elements has also provided a rich source of inspiration for many designers.

Have a look at three or four different renderings of the periodic table, either from the above list, or versions you have discovered elsewhere, and write down how their similarities and differences. Do they communicate the same information, or do they offer different glimpses into the lives of the elements? Do any of the renderings manage to communicate the same information, but in different ways? Give an example.

A Periodic Table of Visualisation Methods

As an act of homage to this great visualisation, the visual layout of the table has also been used to create a periodic table of visualisation methods.

You can see the table here: A Periodic Table of Visualization Methods.

To what extent, if any, does this table make use of the idea of "columnar groups" and "periodic rows" to make explicit similarities and relationships between the different visualisation types?

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