A galaxy of elements

Credit: P.J.STEWART/ BORNDIGITAL.CO.UK

When Dmitri Mendeleev unveiled his periodic table of the elements in 1869, his motives in part embraced what can broadly be described as aesthetic impulses. He sought to define the elusive “unity of matter” through the blending of experimental rigour with pythagorean harmonics (see Nature 393, 527; 1998 ). If we recognize that a fundamental instinct for the beauty of implicit order has fired the endeavours of pioneering scientists over the ages, we should also acknowledge the role of aesthetically engaging images in drawing non-professionals into the wonder of scientific understanding.

The new ‘galactic’ version of the periodical table, devised by Philip Stewart of the Department of Plant Sciences at the University of Oxford, UK, is designed to achieve precisely this latter goal. Stewart is by no means the first to transform Mendeleev's rectangular table into a spiral: his scheme stands in a long tradition of alternative configurations, both flat and three-dimensional.

The primary order of the elements is their linear array according to increasing atomic weight (or the positive charge of the nucleus). The secondary relationships in the various schemes have been paraded in various ways, according to the different priorities, interests, needs and intuitions of those who have devised them. Their graphic rendering reflects, with varying degrees of success, the way their designers envisaged the audience: young or old, naive or knowledgeable.

As a boy, Stewart was inspired by a mural at the Exhibition of Science in South Kensington, London, during the Festival of Britain in 1951 — as indeed were others who were later to enter the world of science. The mural, produced by the artist Edgar Longman, depicted the periodic table as a multicoloured, elliptical spiral of box-like sections.

The ellipse as an iconic configuration in modern science has its own history. Before Johannes Kepler's definition in the early seventeenth century of the elliptical tracks of the planets, the circle or sphere was the shape that ruled supreme in defining the most perfect of cosmic orders. It is interesting (and unexplained) that, at the same time, ellipses and ovals gained prominence in Baroque ecclesiastic architecture in place of the circles, crosses and polygons favoured in the Renaissance.

Modern astronomy has ensured that we now readily recognize the thrilling dynamism of galaxies in any elliptical array of bright bodies. Stewart's new periodic table links the elements in their primary sequence with the dust of multitudinous stars. The spokes, curved by the pull of a notional attractor to the upper right, are composed of wisps of interstellar cloud. Such overtly starry allusions stand in a subtle balance with the genuine chemical advantages in the relative positioning of the elements and their associations. For example, hydrogen sits “comfortably” above carbon, Stewart explains. Lutetium and lawrencium, which cause problems for the conventional periodic table, can be seen here both as the last of the lanthanides and as the first of the next block of transition metals. The placing of neutronium, ‘element 0’, at the very heart of the galaxy is particularly elegant.

At a time when stunning images of Titan, Saturn's largest moon, from the probe Huygens are being shown on our television screens, with the black-and-white images artificially rendered in colour, it is appropriate to acknowledge the key role played by beauty in engaging a wide range of spectators with science. Engagement is a necessary prelude to communication. As Stewart says: “Science needs the emotions as well the intellect. Young people must have enthusiasm to sustain them in the study of difficult subjects.”

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