How the periodic table changed my life

Credit: Brady Haran/Periodic Table of Videos/Flickr

Sir Martyn Poliakoff has appeared in many of the hundreds of episodes of The Periodic Table of Videos.

I cannot remember when I first saw a periodic table. I guess it was on my classroom wall at school when I was 14, a typical age for British schoolchildren to start studying chemistry in those days. But it has played an unexpectedly large role in my life.

Surprisingly, my first inorganic chemistry textbook, published in 1961, did not include a periodic table at all—presumably it was not considered important. So I persuaded my parents to buy me one. Actually, they bought two: a magnificent blue one, which I hung on the wall of my bedroom and have long since lost, and a second, letter-sized copy, which still hangs in my office more than 50 years on.

I suppose that part of the appeal to me has always been that it combines chemistry and Russia. My father was Russian and had decided that I would be a scientist long before I even knew what science was. He was a physicist, but my math wasn’t good enough to pursue a career in physics. So I became a chemist, and my interaction with the periodic table has continued ever since.

I started my PhD in 1969. I became an inorganic chemist and over the years have carried out research involving more than 50 of the now 118 elements, though I cannot claim to be an expert in any of them. My first serious contact with the periodic table as a teaching tool was when I started lecturing on main-group chemistry while one of my colleagues was on sabbatical. I really enjoyed the descriptive aspects of chemistry, though I’m not sure that all the students shared my enthusiasm, and it was a great opportunity to do live demonstrations in class. I’ve been using the table for teaching ever since.

Credit: Brady Haran/Periodic Table of Videos/YouTube

The big change in my relationship with the periodic table, however, came about almost by chance when I met the talented filmmaker Brady Haran, who suggested that we make a YouTube video about each one of the 118 elements in the table, whether they had actually been observed yet or not. I was understandably hesitant, but fortunately I was eventually persuaded. Together with some of my younger colleagues and our indefatigable technician, Neil Barnes, Brady made the Periodic Table of Videos. The videos have been a huge and ongoing success far beyond our initial expectations.

The real surprise for me has been how much our making the videos has changed my life. It has enabled me to visit places and do things connected with the elements that I could not have imagined. I have been able to explore the elements in a way that few chemists are privileged to do. I’ve met those who mine elements, who refine metals, who synthesize new elements, and many others. I’ve seen extraordinary equipment, and I’ve met many, many people who are truly passionate about chemistry.

It is well known that 2019 is the 150th anniversary of Dmitri Mendeleev’s first publication of his “periodic system.” Fewer people realize that it is also the centenary of the birth of the Italian chemist and writer Primo Levi, who was sent to the concentration camp at Auschwitz during World War II and survived only because he was a chemist. This enabled him to work in the chemistry lab of the synthetic-rubber plant next to the camp while other prisoners suffered laboring outside in the intense cold winter of 1944.

I feel that part of Primo Levi’s greatness as a writer is because he wrote not about the triumphs of chemistry but rather about the joy and satisfaction that chemists experience when successfully carrying out the basic manipulations of their trade—filtration, distillation, and so on. He was a real poet of chemistry.

My partnership with Brady in making our videos has allowed me too to experience that joy and to marvel at the beauty of simple chemistry—explosions, precipitation, and color changes. I would never have imagined that plutonium(III) could have such a beautiful purple/violet color! So, in this celebratory year, let us not forget the magic of chemistry that we as chemists are privileged to enjoy.

Credit: Courtesy of Julie Ezold

Julie Ezold watches as daughter Kyrsten works a “ball manipulator” during a classroom visit. The device gives kids an idea of what it’s like for chemists handling radioactive substances to work remotely.

If you had told me 10 years ago that I would be part of an international team of experts who would discover a new element, I would have said, “I don’t think so.” But that is exactly what happened. I am honored to have been part of the discovery of element 117, tennessine

I have been fascinated by the periodic table of the elements since my first chemistry class. The periodic table listed in my advanced chemistry textbook went only to lawrencium (element 103) and identified elements 104–6 as “discovered” but not yet named. Fast-forward to today, and all the elements in the seventh row of the periodic table have been filled in along with their names.

To make an element is no small feat. For instance, to make tennessine, we needed to bombard a target made of the isotope berkelium-249 with a beam of calcium-48 ions. The U400 cyclotron at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia, was responsible for supplying the 48Ca beam. The staff at Oak Ridge National Laboratory synthesized the 249Bk target material using the High Flux Isotope Reactor (HFIR) and purification techniques within the Radiochemical Engineering Development Center.

Credit: Carlos Jones/ORNL

After element 117, tennessine, was officially named, the team at Oak Ridge National Lab celebrated with a luncheon and new version of the periodic table (Julie Ezold pictured at left).

At Oak Ridge, we don’t produce only 249Bk. We also synthesize materials like californium-252 and einsteinium-253, which are derived from curium and are used for research and industrial applications. In fact, berkelium-249 is made at the same time we make californium-252. It’s a by-product of the same process.

Making these materials can take a long time: 3 months to make a curium target and about 4–6 months to irradiate it in the HFIR. After this, we have to chemically separate the material we’re after, like berkeleium-249, and then transfer it to a glove box for further purification, which can take about 4 months. In total, all these steps can involve on the order of 75 staff members.

As the californium-252 program manager, I’m responsible for the technical aspects of making these materials. Coordinating all these activities is exciting and can be challenging at times.

The discovery of tennessine was a herculean effort requiring the expertise and facilities of two US national laboratories, two Russian national laboratories, and two US universities. Hundreds of scientists, engineers, technicians, and skilled craft workers were essential for this discovery. Being a part of this scientific event has been epic not only for me and my career but also in my interactions with my family and our community.

Since the discovery, I have been asked to present at many professional society and community forums. I have presented at local schools for their teachers’ in-service days and at high school assemblies for their science classes. My most memorable presentation, though, was to my daughter’s second-grade class.

The challenge of presenting to 7-year-old students is they haven’t yet learned about atoms or elements. I had to completely change my approach to speaking with them. I used a shower curtain with the periodic table to show where calcium and berkelium were located. They had enough math to add the 20 protons of calcium and the 97 protons of berkelium to get 117.

I showed the cool video that Lawrence Livermore National Laboratory developed after the initial discovery of tennessine. After my talk, the class asked amazing questions and had a decent understanding of the experiment. Their questions included “How long does this element last?” and “What does it do?” During this time, my daughter told me I was a “rock star,” which is high praise from a 7-year-old.

Because of my role in element 117’s discovery, I have become active in the international superheavy-element community. I have had the honor of chairing technical sessions with the world leaders of superheavy-element research. I have been invited to give talks regarding the production and purification of the materials that will be needed to discover elements beyond oganesson (element 118). I’ve also become engaged with university professors and students studying heavy elements. It is a joy to work with the next generation of scientists whose research continues expanding our understanding of the periodic table. I am eternally grateful for the opportunities afforded me by helping discover tennessine and to be part of the ever-changing periodic table of the elements.

Credit: Riken

The team that synthesized nihonium gathers at the Tokyo National Museum during a commemorative ceremony to celebrate naming the new element. Hiromitsu Haba is the sixth person from the right.

Since its conception by Dmitri Mendeleev in 1869, the periodic table has grown and evolved. In my school days, the table ended with element 103, lawrencium. Now, 118 elements fit perfectly in its seven familiar rows.

But how far will it go? How many elements will we be able to create—and how will the periodic table expand to accommodate them?

Today, transactinide elements (those with an atomic number greater than or equal to 104) are typically called superheavy elements. These species have been artificially synthesized in heavy-ion-induced nuclear fusion reactions. A projectile nucleus is accelerated to about 10% of the speed of light and aimed at a target nucleus in the hopes that they will fuse together in a new heavy atom. Because the probability that the nuclei will fuse together is extremely low, scientists have to run synthesis experiments for weeks or even months to generate only one new atom.

After World War II, scientists created superheavy elements at powerful accelerator facilities in the US, Russia, and Germany, competing with one another for prestige. In September 2003, a team led by Kosuke Morita at the research institute Riken, in Japan, entered into the fierce competition. I was part of that team, developing materials for the accelerator’s ion source and radioactive targets and taking shifts monitoring experimental devices and collected data. Dreaming of the birth of Japan’s first element, we aimed to synthesize element 113 by bombarding a bismuth-209 target with zinc-70 ions. In 2004, we detected the first nucleus of element 113 by measuring nuclei formed during its decay: bohrium-266 (element 107) and dubnium-262 (element 105). We confirmed this α-decay chain by creating another nucleus of element 113 in 2005. But those two experiments did not fulfill the criteria for officially creating a new element because the decay chains weren’t extensive enough and because of a lack of firm connections to known nuclei.

Credit: Riken

A plaque honoring the discovery of nihonium at Riken sits at the front gate of its Wako campus, in Japan.

We continued the experiments for another 7 years, until in 2012, we observed a very convincing decay chain containing not only bohrium-266 and dubnium-262 but also lawrencium-258 (element 103) and mendelevium-254 (element 101, named after Mendeleev).

Our dream came true at last on Dec. 30, 2015, when the International Union of Pure and Applied Chemistry (IUPAC) made it official and verified that our team had discovered element 113. We proposed the name “nihonium” and the symbol “Nh” for the new element. Nihon is the way to say “Japan” in Japanese.

The name makes a direct connection to the nation where 113 was discovered and also celebrates the fact that it is the first element in the history of the periodic table to be discovered in, and to be named after, an Asian country. Nihonium was widely lauded in TV news programs and newspapers in Japan. Upon hearing about the element discovered in their own country, people of all ages in Japan were proud of the nation’s contribution to science.

But our work is not yet done. The search for superheavy elements beyond element 118 is a great challenge. The probabilities of producing elements 119 and 120 are far lower than those of producing the superheavy elements already created. Technological improvements are therefore needed. The construction of new accelerator facilities and the development of new experimental devices have already started in institutes such as Riken and the Joint Institute for Nuclear Research, in Russia. Meanwhile our team at Riken has started to search for element 119 together with Oak Ridge National Laboratory, in the US.

When I talk about nihonium in public lectures, most people ask me about its chemical properties and whether it will have practical uses in the future. We can make it only in very small quantities that have short lifetimes, forcing us to study the properties of element 113 one atom at a time. It is not conceivable that weighable quantities of any superheavy element will be produced in the near future, and they will most likely have next to no immediate practical use.

Research on superheavy elements, however, is important from both a fundamental and technological perspective, so the challenges are worth it. Theoretical chemists predict that the electron orbitals of these elements’ atoms will be affected by relativistic effects, so any experimental investigation of their properties will be fascinating. The superheavies are thus good laboratories in which to benchmark theoretical models and refine them, helping us better understand atomic nuclei and atoms.

Credit: Courtesy of Eric Scerri/YouTube

Eric Scerri travels the world lecturing about the history and current state of the periodic table.

It feels like the periodic table has been part of my life for as long as I can recall. I remember how during high school in London, all the individual facts I had learned in chemistry up to that point suddenly began to connect when I was introduced to the periodic table.

I then took undergraduate chemistry at the University of London, and I earned a master’s degree in physical chemistry. My liking for the history of science and for a general philosophical understanding of science drove me to become a graduate student at King’s College London, where I obtained the school’s first PhD in the history and philosophy of chemistry. My thesis was on the reduction of the periodic system to quantum mechanics, or, in plain terms, on the degree to which quantum mechanics has so far succeeded in explaining the periodic system from first principles.

Fifteen years later, in 2007, Oxford University Press published my first book on the periodic table, The Periodic Table: Its Story and Its Significance, which I am pleased to say has been very well received. A second edition is about to appear. Few people seem to have been drawn to writing books on this topic, which has worked to my advantage. During this International Year of the Periodic Table, I have been invited to speak in 10 countries so far, including Russia—specifically Saint Petersburg, where Dmitri Mendeleev made his momentous discovery in 1869.

Now, let me return to a favorite topic: the link between the periodic table and quantum mechanics, which I think is still relevant today. As is well known, quantum theory began to explain chemical periodicity when Niels Bohr suggested that the similarity among elements in the same group of the periodic table was due to their sharing analogous electronic configurations. Then came the realization that electrons behave as waves as much as particles, described by the Heisenberg uncertainty and Pauli exclusion principles.

Credit: Courtesy of Eric Scerri/Oxford University Press

The second edition of Eric Scerri’s inaugural book on the periodic table will release soon.

All this led to the now-familiar four-quantum-number description of electron configuration (for example, the electron in hydrogen can be described as having the four quantum numbers n = 1, l = 0, m_l = 0, and m_s = +½). Here, at least in principle, was an explanation of the periodic system that had been discovered some 50 years before.

However, some details, such as the precise order in which the atomic orbitals were being filled with electrons, was still unknown. The order itself was summarized by Madelung’s rule of thumb, established by observation, that orbitals are occupied in the order of increasing values of n + l, or the sum of the first two quantum numbers. As the theoretician Per-Olov Löwdin stated in a paper to commemorate the 100th anniversary of Mendeleev’s 1869 discovery, the challenge remained one of deriving this rule of thumb from first principles (Int. J. Quantum Chem. 1969, DOI: 10.1002/qua.560030737). Although many attempts have been mounted, the general opinion is that the rule has not yet been successfully derived.

Then some years ago, another theoretician, W. H. Eugen Schwarz, along with colleague Shu-Guang Wang, pointed out that the Madelung rule fails to provide the precise order of orbital occupation in all atoms except for those in the s-block, rendering a derivation unnecessary (Int. J. Quantum Chem. 2009, DOI: 10.1002/qua.22277).

Not everybody shares this view, though, because the rule can be more correctly interpreted as providing the differentiating electron as atomic number increases. For example, the configuration of potassium is [Ar] 4s¹, that of calcium is [Ar] 4s², and that of scandium is [Ar] 3d¹4s². So 4s electrons differentiate potassium and calcium from their previous elements, and 3d electrons differentiate first transition elements as atomic number increases. That means Madelung’s rule fails to provide the order of orbital occupation for atoms like scandium, but it remains fully valid in thinking of the periodic table as a whole.

In conclusion, Löwdin’s challenge still stands in the way of any claim that there exists a full theoretical explanation for chemical periodicity. In other words, the underlying basis of the periodic table is still not fully understood. Paul Adrien Maurice Dirac’s famous claim that all of chemistry has been solved, in principle, remains to be fulfilled. As a philosopher of science, I still consider this to be an important question that is worth focusing on and one that is important in chemical education, which increasingly insists on “putting atoms first.”

My work appeared in Science for the first time in August 2017, one of the proudest achievements of my life. Yet the published piece wasn’t a scientific article. It was poetry. One hundred nineteen haiku to be specific, one for each of the 118 known elements of the periodic table, plus an extra poem for element 119, ununennium, not yet synthesized.

If you had told me when I was growing up that I’d be published in a scientific journal, I would have been pleased but not startled. If you’d told me I’d be published there as a poet, I would have been astounded. I grew up in London, where it was common to specialize early in a subject area. By the last 2 years of high school, I was studying chemistry, physics, mathematics . . . and nothing else. No history, no foreign languages, no art, no literature. I didn’t even stray as far as biology!

Chemistry was the subject that I enjoyed most, partly because of my superb teacher, Jane Angliss. I can’t remember if she was the person who introduced me to the periodic table, but it was in her classes that I learned my way around its first few rows, meeting the halogens, the noble gases, the transition metals. With Sally Lampkin, my lab partner, I measured and mixed chemicals, heated them with a Bunsen burner, observed their reactions.

Credit: Courtesy of Mary Soon Lee

I went on to study mathematics and computer science at the University of Cambridge, worked for an artificial intelligence company, returned to college to earn a master’s degree in astronautics and space engineering, then moved to the US, hoping to work in the space industry. It didn’t turn out as I’d hoped. I found a job yet couldn’t start working because of a delay in the issuing of work permits. In the interim, with time on my hands, I wrote. I wrote and found that I liked it so much that I didn’t want to set it aside.

For years, I happily wrote short stories—science fiction and fantasy tales that appeared in magazines such as Analog and Fantasy & Science Fiction. After my second child was born, I switched to poetry because that was easier to complete in my limited spare time. And one day, I wrote a haiku for hydrogen, the first element in the periodic table:

Credit: Ten Speed Press, an imprint of Penguin Random House

Mary Soon Lee’s new book Elemental Haiku will release in October.

To my great delight, my elemental haiku found a home in Science, both in the printed journal and in an online interactive version of the periodic table, where you click on an element to see the corresponding haiku. This October, they will appear in a book from Ten Speed Press, complete with short explanatory notes that I’ve added, plus wonderful illustrations by Iris Gottlieb.

For haiku aficionados, I should clarify that I use the term haiku loosely. I tried to capture some of the succinctness and juxtaposition of classical Japanese haiku, and I followed a five-seven-five syllable pattern, but my haiku lack the seasonal references and wider resonances of haiku by poets Matsuo Bashō and Yosa Buson and Kobayashi Issa.

Instead of offering insights about nature and humanity, I think of them as tiny tributes to each element. If I am lucky, collectively they form a larger tribute to science, the great human endeavor to fathom our universe. And, if I am very lucky, maybe they will wake an excitement for chemistry or biology or astronomy in readers who hadn’t previously had an interest in science. That would mean a lot to me.