Braving the elements
Dmitri Mendeleev, the man generally attributed with the creation of the first periodic table, had a hell of a biography. Born in Siberia, the youngest of fourteen children, Mendeleev lost his father in 1847, when the boy was 13. Boldly for the time, his mother took over a local glass factory to support the family and managed the male craftsmen working there. Then the factory burned down. Pinning her hopes on her sharpminded son, she bundled him up on horseback and rode 1,200 miles across the steppes and steep, snowy Ural Mountains to an elite university in Moscow – which rejected Dmitri because he wasn’t of local stock. Undaunted, Mama Mendeleev bundled him back up and rode 400 miles farther, to his dead father’s alma mater in St. Petersburg. Just after seeing him enrolled, she died.
Mendeleev proved to be a brilliant student. After graduation, he studied in Paris and Heidelberg, where the eminent Robert Bunsen supervised him for a spell (the two clashed personally, partly because Mendeleev was moody and partly because of Bunsen’s notoriously loud and foulfumed lab). Mendeleev returned to
St. Petersburg as a professor in the 1860s and there began to think about the nature of elements, work that culminated in his famous periodic table of 1869.
Many others were working on the problem of how to organise elements, and some even solved it, however haltingly, with the same approach as Mendeleev. In England, a thirty–something chemist named John Newlands presented his make-shift table to a chemistry society in 1865. But a rhetorical blunder doomed Newlands. At the time, no one knew about the noble gases (helium through radon), so the top rows of his periodic table contained only seven units. Newlands whimsically compared the seven columns to the do-re-mi-fa-sol-la-ti-do of the musical scale. Unfortunately, the Chemical Society of London was not the most whimsical audience, and they ridiculed Newlands’s nickelodeon chemistry.
The more serious rival to Mendeleev was Julius Lothar Meyer, a German chemist with an unruly white beard and neatly oiled black hair. Meyer had also worked under Bunsen at Heidelberg and had serious professional credentials. Among other things, he’d ﬁgured out that red blood cells transport oxygen by binding it to haemoglobin. Meyer published his table at practically the same time as Mendeleev, and the two even split a prestigious pre-Nobel Prize called the Davy Medal in 1882 for co-discovering the “periodic law”. (It was an English prize, but Newlands was shut out until 1887, when he earned his own Davy Medal.) While Meyer continued to do great work that added to his reputation – he helped popularize a number of radical theories that turned out to be correct – Mendeleev turned cranky, a queer ﬁsh who, incredibly, refused to believe in the reality of atoms. (He would later also reject other things he couldn’t see, such as electrons and radioactivity.) If you had sized up the two men around 1880 and judged which was the greater theoretical chemist, you might have picked Meyer. So what separated Mendeleev from Meyer and the four other chemists who published tables before them, at least in history’s judgment?
First, more than any other chemist, Mendeleev understood that certain traits about elements persist, even if others don’t. He realised that a compound like mercuric oxide (an orange solid) doesn’t somehow “contain” a gas, oxygen, and a liquid metal, mercury, as others believed. Rather, mercuric oxide contains two elements that happen to form a gas and a metal when separate. What stays constant is each element’s atomic weight, which Mendeleev considered its deﬁning trait, very close to the modern view.
Second, unlike others who had dabbled in arranging elements into columns and rows, Mendeleev had worked in chemistry labs his whole life and had acquired a deep knowledge of how elements felt and smelled and reacted, especially metals, the most ambiguous and knotty elements to place on the table. This allowed him to incorporate all 62 known elements into his columns and rows. Mendeleev also revised his table obsessively, at one point writing elements on index cards and playing a sort of chemical solitaire in his ofﬁce. Most important of all, while both Mendeleev and Meyer left gaps on their table where no known elements ﬁt, Mendeleev, unlike the squeamish Meyer, had balls enough to predict that new elements would be dug up. Look harder, you chemists and geologists, he seemed to taunt, and you’ll ﬁnd them. By tracing the traits of known elements down each column, Mendeleev even predicted the densities and atomic weights of hidden elements, and when some predictions proved correct, people were mesmerised. Furthermore, when scientists discovered noble gases in the 1890s, Mendeleev’s table passed a crucial test, since it easily incorporated the gases by adding one new column. (Mendeleev denied that noble gases existed at ﬁrst, but by then the periodic table was no longer just his.)
“I admit, Mendeleev has two wives, but I only have one Mendeleev”
Then there was Mendeleev’s outsized character. Like his Russian contemporary Dostoevsky — who wrote his entire novel The Gambler in three weeks to pay off desperate gambling debts — Mendeleev threw together his ﬁrst table to meet a textbook publisher’s deadline. He’d already written volume one of the textbook, a 500-page tome, but had got through just eight elements. That meant he had to ﬁt all the rest into volume two. After six weeks of procrastinating, he decided in one inspired moment that the most concise way to present the information was in a table. Excited, he blew off his side job as a chemistry consultant for local cheese factories to compile the table. When the book appeared in print, Mendeleev not only predicted that new elements would ﬁt into empty boxes beneath the likes of silicon and boron, but he also provisionally named them. It couldn’t have hurt his reputation (people seek gurus during uncertain times) that he used an exotic, mystical language to create those names, using the Sanskrit word for beyond: eka-silicon, eka-boron, and so on.
A few years later, Mendeleev, now famous, divorced his wife and wanted to remarry. Although the conservative local church said he had to wait seven years, he bribed a priest and got on with the nuptials. This technically made him a bigamist, but no one dared arrest him. When a local bureaucrat complained to the tsar about the double standard applied to the case — the priest was defrocked — the tsar primly replied, “I admit, Mendeleev has two wives, but I have only one Mendeleev.” Still, the tsar’s patience wasn’t inﬁnite. In 1890, Mendeleev, a self-professed anarchist, was booted out of his academic post for sympathising with violent leftist student groups.
It’s easy to see why historians and scientists grew attached to Mendeleev’s life’s tale. Of course, no one would remember his biography today had he not constructed his periodic table. Overall, Mendeleev’s work is comparable to that of Darwin in evolution and Einstein in relativity. None of those men did all the work, but they did the most work, and they did it more elegantly than others. They saw how far the consequences extended, and they backed up their ﬁndings with reams of evidence. And like Darwin, Mendeleev made lasting enemies for his work. Naming elements he’d never seen was presumptuous, and doing so infuriated the intellectual successor of Robert Bunsen — the man who discovered “eka-aluminium” and justiﬁably felt that he, not the rabid Russian, deserved credit and naming rights.
The discovery of eka-aluminium, now known as gallium, raises the question of what really drives science forward – theories, which frame how people view the world, or experiments, the simplest of which can destroy elegant theories. After a dustup with the theorist Mendeleev, the experimentalist who discovered gallium had a deﬁnite answer. Paul Emile François Lecoq de Boisbaudran was born into a winemaking family in the Cognac region of France in 1838. Handsome, with sinuous hair and a curled moustache, prone to wearing stylish cravats, he moved to Paris as an adult, mastered Bunsen’s spectroscope [a device which uses the properties of light to find the elemental composition of different materials] and became the best spectroscopic surgeon in the world.
Lecoq de Boisbaudran grew so adroit that in 1875, after spotting never-before-seen colour bands in a mineral, he concluded, instantly and correctly, he’d discovered a new element. He named it gallium, after Gallia, the Latin name for France. (Conspiracy mongers accused him of slyly naming the element after himself, since Lecoq, or “the rooster,” is gallus in Latin.) Lecoq de Boisbaudran decided he wanted to hold and feel his new prize, so he set about purifying a sample of it.
It took a few years, but by 1878 the Frenchman ﬁnally had a nice, pure hunk of gallium. Though solid at moderate room temperature, gallium melts at 29°C, meaning that if you hold it in the palm of your hand (because body temperature is about 37°C), it will melt into a grainy, thick puddle of pseudoquicksilver. It’s one of the few liquid metals you can touch without boiling your ﬁnger to the bone. As a result, gallium has been a staple of practical jokes among the chemistry cognoscenti ever since. One popular trick, since gallium moulds easily and looks like aluminium, is to fashion gallium spoons, serve them with tea, and watch as your guests recoil when their Earl Grey “eats” their utensils.
“Gallium is a staple of practical jokes among the chemistry cognoscenti”
Lecoq de Boisbaudran reported his ﬁndings in scientiﬁc journals, rightfully proud of his capricious metal. Gallium was the ﬁrst new element discovered since Mendeleev’s 1869 table, and when the theorist Mendeleev read about de Boisbaudran’s work, he tried to cut in line and claim credit for gallium based on his prediction of eka-aluminium. Lecoq de Boisbaudran responded tersely that, no, he had done the real work. Mendeleev demurred, and the Frenchman and Russian began debating the matter in scientiﬁc journals, like a serialised novel with different characters narrating each chapter. Before long, the discussion turned acrimonious. Annoyed at Mendeleev’s crowing, Lecoq de Boisbaudran claimed an obscure Frenchman had developed the periodic table before Mendeleev and that the Russian had usurped this man’s ideas — a scientiﬁc sin second only to forging data. (Mendeleev was never so good about sharing credit. Meyer, in contrast, cited Mendeleev’s table in his own work in the 1870s, which may have made it seem to later generations that Meyer’s work was derivative.)
For his part, Mendeleev scanned Lecoq de Boisbaudran’s data on gallium and told the experimentalist, with no justiﬁcation, that he must have measured something wrong, because the density and weight of gallium differed from Mendeleev’s predictions. This betrays a ﬂabbergasting amount of gall, but as science philosopher-historian Eric Scerri put it, Mendeleev always “was willing to bend nature to ﬁt his grand philosophical scheme”.
The only difference between Mendeleev and crack-pottery is that Mendeleev was right: Lecoq de Boisbaudran soon retracted his data and published results that
corroborated Mendeleev’s predictions. According to Scerri, “the scientiﬁc world was astounded to note that Mendeleev, the theorist, had seen the properties of a new element more clearly than the chemist who had discovered it.” A literature teacher once told me that what makes a story great – and the construction of the periodic table is a great story – is a climax that’s “surprising yet inevitable”. I suspect that upon discovering his grand scheme of the periodic table, Mendeleev felt astonished – yet also convinced of its truth because of its elegant, inescapable simplicity
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