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The Beauty of Chemistry: Art, Wonder, and Science



The Beauty of Chemistry: Art, Wonder, and Science PDF

Author: Philip Ball , Wenting Zhu

Publisher: The MIT Press

Genres:

Publish Date: May 11, 2021

ISBN-10: 0262044412

Pages: 392

File Type: PDF

Language: English

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Book Preface

Chemistry, more than any other science, is a confluence of the practical and the sublime. It’s best known in the first of these guises: as the prosaic source of the substances all around us, by which our lives are increasingly shaped for better or worse. We are apt, like ungrateful children, to take for granted the dyes that clothe us in fashionable and flattering shades, the artificial scents that hide our own, the medicines that relieve our aches and ailments, the tiny slices of high- tech semiconducting alloys in our smartphones. We grumble (and so we should, although not at chemistry) about the pollutants in our air and water, the plastics clogging our rivers and seas. Chemistry gives us the fabrics of our existence: polyesters and polycarbonates, touchscreens and batteries, non- stick pans and non- drip paint. We depend on its bounty but fear its baneful influence: it is both problem and cure, nemesis and savior.
The chemical sublime is less familiar, but this book will introduce you to it. We will show some of the astonishing beauty that resides in chemical products and processes. This beauty too often passes unseen, or at least unacknowledged as chemical in nature. We can marvel at the delicacy of a snowflake, or the glory of a flower and its heady fragrance, while failing to realize that chemistry is at work here every bit as much as it is in oil refineries and pharmaceutical plants.
There doesn’t seem to be a word for people who take delight in stuff, but there ought to be. We propose that they be called ousiophiles, from the Greek ousia, meaning essence or substance. Chemists are usually ousiophiles: they delight in tangible material, in texture and heft, in luster and pliancy. They want to touch and feel things, to smell and taste them. It’s in this impulse that a love of chemistry resides; people who have it are often drawn to study the subject.
The Italian writer Primo Levi was undoubtedly an ousiophile. Levi wrote two particularly famous books, and one of them was The Periodic Table, a love letter to the primal substances, the elements, of chem-istry. The book’s title alludes to the iconic scheme used to arrange the chemical elements and which reveals the hidden order among them. Each chapter of Levi’s book is named after a chemical element— argon, hydrogen, zinc, iron, potassium, and more— and makes its titular substance a character in a story, generally drawn from an episode in Levi’s life. He revels in the materiality of these substances: chro-mium, mixed into an orange anti- rust paint in the factory outside Turin where Levi worked after the Second World War, or the “generous good nature of tin, Jove’s metal.” The Periodic Table brought a chem-ical sensibility to the notice of readers who might have remembered nothing from their school chemis-try lessons, not even the blocky format of the periodic table itself.
Levi’s other famous book is If This Is a Man, an account of the time he spent in the concentration camp at Auschwitz. There his knowledge of chemistry saved his life by making him eligible to work in the laboratory that served the Buna industrial plant, set up to make artificial rubber for the Nazi war effort. If it had not been for that assignment, it is unlikely Levi would have survived in Auschwitz during the harsh winter of 1944. Because he did, the world got to see this vital, harrowing, deeply humane account of atrocity.
Ordering the elements
To some chemists, the periodic table has almost the status of a catechism. Within its rows and columns of elemental symbols is encrypted much of what chemistry is about. It’s not just that these elements are the building blocks of the subject, the varieties of atom from which all the physical world is constructed. The shape and topography of the table, gathering together elements with shared chemical properties, reflect the principles that govern atomic unions, dictating how elements may be combined to produce all the beauty and richness, the hazards and surprises, of the chemical world. To the initiated, the location of carbon (say) hints at its role in living things, while it is because the alkali metals come first in each row of the table that the chemist knows they will be highly reactive, dangerous to the touch. By the same token, by ending each row the inert gases such as xenon and argon are granted their lack of reactivity. Levi used them as metaphors for the character of the Jews of Turin from whom he was descended, alluding to their “attitude of dignified abstention.”
The periodic table was internationally celebrated in 2019 to mark the 150th anniversary of its first appearance. (By coincidence this was also the centenary of Primo Levi’s birth.) In 1869 an early version of the table, sketchy and full of gaps, was unveiled by the Siberian chemist Dmitri Mendeleev. He was by no means the first to recognize that the chemical elements can be grouped into families in which all the members show similar behavior. And if Mendeleev had not discerned the way these groups fit together, others would surely have done so around the same time. But Mendeleev was almost alone in trusting this deep structure enough to leave gaps where he figured new elements, as yet undiscovered, should exist. Those gaps were filled in due course, and Mendeleev’s predictions about the properties of these missing elements were borne out.
The periodic table of the chemical elements doesn’t self- evidently deserve the reverence that many chemists seem to feel for it. It’s not a terribly elegant structure. With its rows of elements rising to turret- like peaks at either end and the long block of elements (called the transition metals) in the middle, the shape resembles a somewhat ungainly modernist housing development. Besides, chemists aren’t even agreed today on exactly how the table should be drawn; there are still disputes about where some of the elements should be placed.
All the same, the recognition of this hidden order among the profusion of elements implied that there are deeper principles that determine their chemical properties. It took a further half- century after Mendeleev’s publication to figure out what these principles are.
A key part of that puzzle was supplied in 1916 by the American chemist Gilbert Lewis, who argued that the chemical properties of the elements could be understood from the nature of the atoms of which they are composed. In the early years of the twentieth century, scientists discovered that atoms are not dense, featureless little balls of matter as had once been supposed, but have some internal structure composed from yet more fundamental particles. They have a very dense nucleus, which has a positive electrical charge and contains particles called protons (and also electrically neutral particles called neutrons, not discovered until 1932). Around the nucleus are arrayed much lighter particles called electrons, which have a charge equal in size but opposite in sign to that of the proton. Most of the atom is empty space; in one of the earliest pictures they were envisioned as tiny solar systems, with the nucleus as a kind of sun orbited by planetary electrons. This is too simplistic an image, but it was good enough to be useful for understanding how atoms of matter are constituted.
Discovering the internal structure of atoms was no small feat. A carbon atom (say) is just 0.17 millionths of a millimeter across, which is far too small to see inside with any microscope. It is not easy even to believe in objects so small; in the early twentieth century, some scientists (including Mendeleev) did not. But they do exist— we’re now certain of that.
Lewis suggested that there is a “kernel” in each atom, made up of the nucleus plus some electrons, with a net positive charge equal to the number of the column in the periodic table in which it sits. In other words, elements in the first column (the alkali metals) have a kernel with a charge of +1, and so on. Around this kernel is a “shell” of as many electrons as are needed to balance out the charge. For the alkali metals, the shell has a single electron.
Lewis proposed that this outer shell can contain up to 8 electrons: this maximum number is found in the inert gases. This idea makes some sense of the fact that (if you ignore the wide block of transition metals in the periodic table) there are eight columns in each row: the so- called “main block” elements.
He proposed that the electrons can be thought of as sitting at the corners of a cube. Why a cube? That was simply a neat way to imagine the atom, since cubes have eight corners. Lewis didn’t want to suggest that atoms literally have this shape. When atoms join together to form chemical bonds— linking them into groupings called molecules— they can then be imagined (again, not literally) as cubes sharing corners or edges. The electrons at the shared corners are then assigned to both atoms, and each pair of shared electrons makes a chemical bond.
Why should the outer shell of electrons involved in bonding have this eightfold capacity? Lewis had no explanation. Nor could he really explain why hydrogen and helium poke out at each end of the main blocks of the periodic table, with no elements in between them, nor why the transition metals interrupt the third and subsequent columns of the main block. These aspects of the table’s structure became understood within a few years of Lewis’s suggestion, once physicists worked out the fundamental rules governing the way electrons are arranged around an atomic nucleus. These rules emerge from the theory called quantum mechanics, which describes how very small particles like electrons and atoms behave. Quantum mechanics makes perfect sense of the blocky shape of the periodic table.
It’s a source of great satisfaction to scientists when they are able to explain something com-plicated in terms of ideas that are simpler. The motions of the planets in the night sky, as seen from Earth, look perplexingly complex, even though there are regularities to them. But once you understand that the Earth is one of those planets too, traveling in near- circular (elliptical) orbits around the Sun, the pattern becomes clear and what previously seemed intricate and even a little awkward now takes on a certain elegance. It was the same for the elements: once we understood them in terms of the way electrons are organized around their constituent atoms, apparent complexity gave way to deep simplicity.
A sense of wonder
Many scientists find a genuine aesthetic pleasure in such abstract reasoning. They look at the periodic table of the elements, and they see beauty. You might share that response— or you might not. Maybe it takes a particular frame of mind to equate intellectual understanding with beauty.
You do not, however, need to have such a mind in order to appreciate the beauty of chemistry. We hope that this book will persuade you that chemistry unfolds with a beauty that anyone can enjoy. We hope that the text will not just explain what it is you are seeing in these images but might also deepen the visual experience. We agree with the famous physicist Richard Feynman that scientific understanding does not diminish a sense of wonder and delight, but on the contrary may enhance it. Affronted at the suggestion of an artist friend that the scientist “takes apart” a flower and renders it “a dull thing,” Feynman responded:

I can appreciate the beauty of a flower. At the same time, I see much more about the flower than he sees. I could imagine the cells in there, the complicated actions inside, which also have a beauty. I mean it’s not just beauty at this dimension, at one centimeter; there’s also beauty at smaller dimensions, the inner structure, also the processes. The fact that the colors in the flower evolved in order to attract insects to pollinate it is interesting; it means that insects can see the color. It adds a question: does this aesthetic sense also exist in the lower forms? Why is it aesthetic? All kinds of interesting questions, which the science knowledge only adds to the excitement, the mystery and the awe of a flower. It only adds. I don’t understand how it subtracts.

We will sometimes invite you to regard the visual wonders in these pages in terms of atoms doing things— organizing themselves, exchanging and rearranging their electrons, bouncing off one another, or scattering light. We can’t see those processes directly, but we can infer them and deduce their consequences. It’s the peculiar power of chemistry to connect those two aspects— the atomic and the everyday— that makes it both a glorious and a useful science, a discipline that reveals how the world we experience emerges from one that is altogether stranger, more elusive, and in some sense mysterious. The words of another great scientist, Charles Darwin, while coined in a different context (to describe the evolution of life on earth), are entirely apposite here too, and Darwin would surely have approved of how they may speak to the unity of the sciences as well as the splendor of the natural world they describe:

There is grandeur in this view of life˜.˜.˜. whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.

Content

ELEMENTAL: THE CHARISMA OF CHEMISTRY 1
1 EFFERVESCENT: THE BEAUTY OF BUBBLES 7
2 ORDERLY: THE CHARM OF CRYSTALS 39
3 INSOLUBLE: THE POWER OF PRECIPITATION 79
4 EXUBERANT: THE DELIGHT OF DENDRITIC GROWTH 113
5 INCENDIARY: THE FASCINATION OF FLAMES 161
6 GALVANIZING: THE ENCHANTMENT OF ELECTROCHEMISTRY 199
7 CHROMATIC: THE CURIOSITY OF COLOR CHANGES IN PLANTS 231
8 CALESCENT: THE HELPFULNESS OF HEAT 271
9 ORGANIC: THE CONTORTIONS OF CHEMICAL GARDENS 297
10 CREATIVE: THE PROFUSION OF PATTERNS 327
POSTSCRIPT: ART, WONDER, AND SCIENCE 355
ACKNOWLEDGMENTS 359
APPENDIX: MOLECULES AND STRUCTURES 361
GLOSSARY 375
SOURCES OF QUOTATIONS 379
INDEX 381


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