The scientist who systematized all the known elements in the universe was about to throw everything away for love. In April, 1881 Dmitri Ivanovich Mendeleev was internationally renowned for his creation of the periodic table that revealed the simple, yet elegant structure underlying all matter, but he was prepared to kill himself unless the woman he loved agreed to marry him.

Anna Ivanovna Petrova, a twenty-year-old art student from the small Cossack village of Uryupinskaya in Southern Russia, had already turned him down twice in the last three years. Now the famous scientist had followed her to Rome where Anna’s father sent her to study (and to keep her beyond the reach of Mendeleev’s advances, who, after all, was forty-seven years old and married with two teenage children). But the man whose passion for science drove him to harness the mysteries of atomic valence was ultimately overpowered by elements of human chemistry that he could not control.

Of course, Dmitri Mendeleev wasn’t supposed to survive long enough to take his own life. Nearly thirty years earlier, on June 7, 1855, dense black clouds had filled the St. Petersburg sky like “a thick hanging of mourning drapery.” Across the Neva river the bells of St. Isaac’s Cathedral tolled beneath its golden dome, announcing the arrival of the Imperial yacht and its attending funeral procession. From his hospital room at St. Petersburg State University Mendeleev could have watched as the casket of Tsar Nicholas I was transported into the still unfinished Orthodox church, flanked by bishops in their purple velvet mitres. The sudden death of the Tsar, from an illness contracted during the Crimean War, would have offered ample opportunity for Mendeleev to contemplate his own impending mortality.

After experiencing frequent complications due to tuberculosis and “spitting blood,” doctors told the young chemistry student that he only had a short time to live. He was merely awaiting his journey to a drier climate later that summer and the remote chance he might survive. Remarkably, Mendeleev avoided the same fate that took the lives of both his mother and older sister to complete his thesis on chemical isomorphism that very year. He earned a gold medal for excellence with this freshman research and embarked on a scientific trajectory whose ascent few could ever imagine might fall.

After his full advancement to Professor of General Chemistry at St. Petersburg State University, and frustrated that no Russian textbooks existed on the topic, Mendeleev determined that he would write one himself. Spanning four volumes and taking three years to complete, his Principles of Chemistry adopted a personal, conversational style that spoke directly with the reader so that he could properly communicate both the evidence necessary for work in the laboratory and, more importantly, the philosophical underpinnings of the scientific process.

“Experimental and practical data occupy their place,” he wrote, “but the philosophical principles form the chief theme of the work.” For Mendeleev, science wasn’t simply a practical tool, it was a journey of passion and creativity that he emphasized in all of his scientific communication.

I have endeavored to incite in the reader a spirit of inquiry, which, dissatisfied with speculative reasonings alone, should subject every idea to experiment, encourage the habit of stubborn work, and excite a search for fresh chains of evidence to complete the bridge over the bottomless unknown.

This was the same spirit of critical inquiry that he shared with his students in the classroom, speeches that would be followed by “thunders of applause” from his attentive audience.

“During the whole lecture,” wrote his student V.E. Grum-Grzhimailo, “[Mendeleev] taught us how to observe phenomena of everyday life and how to understand them... He imparted on his pupils his skill in observing and thinking, which no one book can give.”

But Mendeleev’s holistic approach to explaining material reality when reduced to its chemical constituents was not always popular with his university colleagues. Some felt “he had too many ideas [while] concerning narrow specific problems, he lacks patience.” The common approach at the time was to teach science through the memorization of established truths, like the rows of Latin verbs that Mendeleev was punished for reciting incorrectly as a boy.

“[T]he chemist of his day was more occupied in adding to the chemical facts than in speculating on the relation between them,” Lord Ernest Rutherford, the British Nobel Prize Winning chemist, would later remark. But it was Mendeleev’s unique combination of an empirical methodology with a speculative nature that drove him to envision novel interpretations of the chemical evidence.

The central problem that chemists faced in 1869 was that there were 63 known elements (today there are 118, though just 94 are naturally occurring) but there was no explanation for the clear patterns that could be observed between groups of elements. These 63 elements—such as lead, nitrogen, or carbon—were substances that couldn’t be broken down into simpler substances. For example, water was thought to be an element in the ancient world, but by passing electricity through water vapor each molecule would break down into two hydrogen atoms and one oxygen atom (H2O) and neither of these could be reduced further. Many of these elements showed periodicity, or clustering around certain characteristics such as boiling point and atomic weight, suggesting that there was an underlying structure. It was identifying this structure that became Mendeleev’s obsession.

One strange pattern Mendeleev thought required explanation was that when the atomic weight of an element increased so did the number of oxygen atoms that would bond with it. But it wasn’t as simple as increased mass increasing the number of valence bonds. Sodium, for example, had an atomic weight of 23 and a valence of 1, the same as potassium with a weight of 39. But there seemed to be a pattern that occurred in clusters of eight. Increase the atomic weight and the valence would increase with it, until you reached the eighth element where the valence pattern started over again. Armed with careful measurements of atomic weight and experiments on these valence bonds (as well as other periodic patterns) Mendeleev attempted to arrange the elements so that all the known similarities would cluster together. Over a three-day period in February, 1869, working almost nonstop, he constructed an elaborate jigsaw puzzle in which one-third of the pieces were missing and many others were badly misshapen.

However, the key to this periodic law as he called it, was that it made specific predictions. Mendeleev felt confident that there were elements that hadn’t been discovered yet and he intentionally left gaps in his table. He predicted that that there should be additional unidentified elements with atomic weights of about 44, 70, and 72 that would fill the holes in his model. Over the next few years all three hypothetical elements were discovered precisely as he predicted (later to be named scandium, gallium, and germanium). By using a combination of precise measurement and creative insight, Mendeleev had intuited order in the very fabric of reality.

When Anna Petrova first met the man whose life would ultimately collide with her own, he was at the height of his international fame. There was no way she could have known that, at the very moment when Mendeleev’s scientific legacy was firmly established, his personal life was already beginning to unravel.

. . . To Be Continued.