A Visual Journey Around the Periodic Table
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THE E LEMENTS A VISUAL JOURNEY AROUND THE PERIODIC TABLE BY HUGH ALDERSEY-WILLIAMS INCLUDING AN INTERVIEW WITH GRAPHIC DESIGNER DAVID SMITH THE ELEMENTS _ THE A VISUAL JOURNEY AROUND THE PERIODIC TABLE _ ELEMENTS: Published by: Science Gallery, Pearse Street, Trinity College, Dublin 2, Ireland A VISUAL JOURNEY AROUND THE PERIODIC TABLE T: +353 (0)1 896 4091 This essay is published in association with the touring exhibition: E: [email protected] ELEMENTS: THE BEAUTY OF CHEMISTRY, created by Science _ Gallery, Trinity College Dublin on the occasion of the Tercentenary of the School of Chemistry at Trinity College Dublin. ISBN: 978-0-9558957-3-9 _ _ The exhibition, launching in the International Year of Chemistry, All rights reserved. No part of this publication is curated by David Grayson, Daniel O’Donovan, Hugh Aldersey-Williams may be reproduced in any form by any and Michael John Gorman, and is a partnership between Science electronic or mechanical means, including Gallery, Trinity College Dublin and the BergamoScienza festival, with photocopy, recording or information storage the assistance of researcher Brigid Lanigan and advisor Silvia Giordani. without written consent from the publisher. _ _ To explore the ELEMENTS exhibition visit www.sciencegallery.com/elements © SCIENCE GALLERY All work remains © of its respective author(s) CONTENTS_ Au Pb Cu Hg 07_ 08_ 08_ 10_ 10_ 12_ C Ca Fe Co 12_ 15_ 12_ 15_ 15_ 16_ 16_ As Na Ar U 16_ 16_ 19_ 19_ Si Ra Pt Ds_ 21_ 21_ 22_ 22_ 26_ 30_ THE ELEMENTS_ A VISUAL EXPLORATION_ Au_ Pb_ _ THE RAW MATERIALS OF EVERYTHING Let’s get one thing straight from the start. textbook for his students at St Petersburg The periodic table does not exist. University. Aware of the growing number The chemical elements exist, but the of chemical elements that had recently been THe periodic table of the elements that we discovered, he wished to bring some order are all taught about at school, in ways to what was fast becoming an unruly jumble. more or less inspired, is no more than The story goes that he sat down at his desk a representational convenience. with the names of all the known elements The chemical elements do have a written out on cards in front of him, and natural sequence. What makes one different began to shuffle them around as in a game of from another is the number of protons in patience. He knew it was important to keep in the nucleus of its atoms. Starting with the mind their natural order by atomic weight. But lightest of them, hydrogen, which has a single he also started to group them according to proton, each subsequent element (helium, their chemical similarities. Corrosion-resistant PEriOdic lithium, beryllium and so on) contains one metals such as gold and silver went together. more proton. This continues all the way up Pungent-smelling elements like chlorine, to the more than one hundred elements we bromine and iodine did too. In this way, he know today. This fundamental fact allows us began to assemble a two-dimensional array. to rank the elements according to their atomic _ weight. It places them in a linear order, but it does no more than that. This alone does not lead us to the familiar two-dimensional grid of IT IS MENDELEEV’S TABLE THAT squares that we call the periodic table, which HAS SURVIVED AS THE ONE THAT is in the end simply a brilliant visual aid, with MAKES THE GREATEST SENSE OF Table less truth about it than the average map. THE CHEMISTRY OF THE ELEMENTS. ‘ELEMENTS: THE BEAUTY OF CHEMISTRY’ explores both the iconic nature _ of the periodic table and the attraction and utility of the elements that lie behind it. But not everything made sense. In some The periodic table is the invention areas, there seemed to be too few elements. of the Russian chemist Dmitrii Mendeleev. Mendeleev’s stroke of genius was to dare Does Not In the 1860s, Mendeleev was writing a to leave gaps in his table for elements Ex01_ i S t_ 01_ 88 2 8 18 THE ELEMENTS_ A VISUAL JOURNEY AROUND THE PERIODIC TABLE_ 32 18 8 Ra 2 RADIUM (226) that hadn’t yet been discovered. This It is Mendeleev’s table that has survived as supremely confident gesture was the key the one that makes the greatest sense of the to Mendeleev’s triumph. From 1869, when chemistry of the elements. In its 142 years, his table was first published in his long- it has required only one major modification awaited textbook, until his death in 1911, – the addition of an extra column on the he had the unique pleasure of hearing the right to accommodate the chemical group news from time to time that a chemist in of elements known as the noble gases, Germany or France or Sweden had found which were unexpectedly discovered around a new element to fill one of these gaps. the turn of the twentieth century. Even the Many people think of Mendeleev’s heavy, radioactive elements discovered periodic table as a scientific discovery, rather since the Second World War have slipped than an invention. Yet it was and remains obediently into place in Mendeleev’s design. simply one table among many candidates. Small wonder, then, that this table has become It has two dimensions because of the a graphic icon. We remember it, happily or necessary constraint of putting it down on not, from the schoolroom. But it now adorns paper so that it could appear in a textbook. coffee mugs, tee-shirts and shower curtains, _ where chemical knowledge is absolutely not required. It is exploited by renowned THE ELEMENTS contemporary artists such as Damien Hirst and Simon Patterson. It prompts questions HAVE ALWAYS BEEN for quizzes and titles for books. It has inspired FASHIONED, TRADED, innumerable variations on the internet where EXCHANGED, ADMIRED there are periodic tables of biscuits and swearwords and much else besides. If there’s AND WORSHIPPED. one thing we love more than a system of order, _ it seems, it’s making a mockery of that system. There would be no need for a During the mid-nineteenth century there periodic table at all if we didn’t know that were quite a few competing tables of the there is something truly special about the elements. Many scientists had noted strange elements, that these are forms of matter relations among the elements, but had which demand to be collected, organised and usually come unstuck by attaching too much presented as some kind of complete system. importance to the numbers that appeared The idea that the material world to govern these relations. These tables have is not merely made up of matter, but of fallen into obscurity. Others are still devised particular types of matter, is very old. From from time to time even today, including the idea that all matter might be made up ones that use more than two dimensions. of versions of a single basic material, perhaps 02_ THE ELEMENTS_ A VISUAL JOURNEY AROUND THE PERIODIC TABLE_ water, the Greek philosopher Empedocles This investigation led him to a highly developed the notion that there were four significant sequence of discoveries. Different elements, adding earth, air and fire to water. waters contained different solid salts, and Aristotle added his authority to this concept from these salts it was sometimes possible such that it persisted for 2,000 years. As a to extract different metals. Water itself was theory of matter, it was sufficiently robust that it also separable into two gases with distinct appeared with minor variations in most ancient properties, hydrogen and oxygen, and so philosophies. It slotted in to a fourfold view even water could no longer be regarded of the world that also included the cardinal as an element. In the year of the French directions and the agricultural seasons. Revolution, 1789, Lavoisier drew up a list _ of ‘simple substances’ that included these newly discovered gases, as well as twenty-one other substances now confirmed as elements, IT IS THE ELEMENTS and eight more substances with distinctive THAT GOVERN OUR chemical behaviour that he was sure contained LIVES, NOT THE new elements that would be obtained in their pure state just as soon as a suitable PERIODIC TABLE. technique was found for converting them. _ Mendeleev’s table, assembled eighty years later, counted sixty-three The four elements comprised different named elements (and four gaps). Today, combinations of four ‘principles’: heat, cold, there are 112 named elements. In June wet and dry. And they corresponded neatly 2011, scientists at the Joint Institute of with the four bodily humours that dominated Nuclear Research confirmed the existence medical understanding for most of this period. of two new arrivals, numbers 114 and With the birth of modern chemistry, 116, which now await official naming. however, it began to be understood that this In many cases, what we know now as scheme was no longer sufficient to explain an element in the scientific sense has long held the full variety of matter. For example, it importance or fascination simply as a material. was clear that metals, while they were The elements have always been fashioned, extracted from the earth, were not themselves traded, exchanged, admired and worshipped. earth. The air we breathe was obviously This is true of the few elements known not the same as the fumes of volcanoes in the ancient world: antimony, arsenic, or the gas that bubbles out of swamps. carbon, copper, iron, gold, lead, mercury, In the late eighteenth century the silver, sulphur, tin.