150 years ago, the periodic table began with one chemist’s vision (2024)

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Every field of science has its favorite anniversary.

For physics, it’s Newton’s Principia of 1687, the book that introduced the laws of motion and gravity. Biology celebrates Darwin’s On the Origin of Species (1859) along with his birthday (1809). Astronomy fans commemorate 1543, when Copernicus placed the sun at the center of the solar system.

And for chemistry, no cause for celebration surpasses the origin of the periodic table of the elements, created 150 years ago this March by the Russian chemist Dmitrii Ivanovich Mendeleev.

Mendeleev’s table has become as familiar to chemistry students as spreadsheets are to accountants. It summarizes an entire science in 100 or so squares containing symbols and numbers. It enumerates the elements that compose all earthly substances, arranged so as to reveal patterns in their properties, guiding the pursuit of chemical research both in theory and in practice.

“The periodic table,” wrote the chemist Peter Atkins, “is arguably the most important concept in chemistry.”

Mendeleev’s table looked like an ad hoc chart, but he intended the table to express a deep scientific truth he had uncovered: the periodic law. His law revealed profound familial relationships among the known chemical elements — they exhibited similar properties at regular intervals (or periods) when arranged in order of their atomic weights — and enabled Mendeleev to predict the existence of elements that had not yet been discovered.

“Before the promulgation of this law the chemical elements were mere fragmentary, incidental facts in Nature,” Mendeleev declared. “The law of periodicity first enabled us to perceive undiscovered elements at a distance which formerly was inaccessible to chemical vision.”

Mendeleev’s table did more than foretell the existence of new elements. It validated the then-controversial belief in the reality of atoms. It hinted at the existence of subatomic structure and anticipated the mathematical apparatus underlying the rules governing matter that eventually revealed itself in quantum theory. His table finished the transformation of chemical science from the medieval magical mysticism of alchemy to the realm of modern scientific rigor. The periodic table symbolizes not merely the constituents of matter, but the logical cogency and principled rationality of all science.

An ordered vision

Mendeleev’s periodic table, published in 1869, was a vertical chart that organized 63 known elements by atomic weight. This arrangement placed elements with similar properties into horizontal rows. The title, translated from Russian, reads: “Draft of system of elements: based on their atomic masses and chemical characteristics.”

150 years ago, the periodic table began with one chemist’s vision (1)

Laying the groundwork

Legend has it that Mendeleev conceived and created his table in a single day: February 17, 1869, on the Russian calendar (March 1 in most of the rest of the world). But that’s probably an exaggeration. Mendeleev had been thinking about grouping the elements for years, and other chemists had considered the notion of relationships among the elements several times in the preceding decades.

In fact, German chemist Johann Wolfgang Döbereiner noticed peculiarities in groupings of elements as early as 1817. In those days, chemists hadn’t yet fully grasped the nature of atoms, as described in the atomic theory proposed by English schoolteacher John Dalton in 1808. In his New System of Chemical Philosophy, Dalton explained chemical reactions by assuming that each elementary substance was made of a particular type of atom.

Chemical reactions, Dalton proposed, produced new substances when atoms were disconnected or joined. Any given element consisted entirely of one kind of atom, he reasoned, distinguished from other kinds by weight. Oxygen atoms weighed eight times as much as hydrogen atoms; carbon atoms were six times as heavy as hydrogen, Dalton believed. When elements combined to make new substances, the amounts that reacted could be calculated with knowledge of those atomic weights.

Dalton was wrong about some of the weights — oxygen is really 16 times the weight of hydrogen, and carbon is 12 times heavier than hydrogen. But his theory made the idea of atoms useful, inspiring a revolution in chemistry. Measuring atomic weights accurately became a prime preoccupation for chemists in the decades that followed.

When contemplating those weights, Döbereiner noted that certain sets of three elements (he called them triads) showed a peculiar relationship. Bromine, for example, had an atomic weight midway between the weights of chlorine and iodine, and all three elements exhibited similar chemical behavior. Lithium, sodium and potassium were also a triad.

Intrinsic order

Every element on this venerated table has its own story. All together, they capture the entire repertoire of known chemistry. Read up on the talesbetween the lines.

E. Otwell

Other chemists perceived links between atomic weights and chemical properties, but it was not until the 1860s that atomic weights had been well enough understood and measured for deeper insights to emerge. In England, the chemist John Newlands noticed that arranging the known elements in order of increasing atomic weight produced a recurrence of chemical properties every eighth element, a pattern he called the “law of octaves” in an 1865 paper. But Newlands’ pattern did not hold up very well after the first couple of octaves, leading a critic to suggest that he should try arranging the elements in alphabetical order instead. Clearly, the relationship of element properties and atomic weights was a bit more complicated, as Mendeleev soon realized.

Organizing the elements

Born in Tobolsk, in Siberia, in 1834 (his parents’ 17th child), Mendeleev lived a dispersed life, pursuing multiple interests and traveling a higgledy-piggledy path to prominence. During his higher education at a teaching institute in St. Petersburg, he nearly died from a serious illness. After graduation, he taught at middle schools (a requirement of his scholarship at the teaching institute), and while teaching math and science, he conducted research for his master’s degree.

He then worked as a tutor and lecturer (along with some popular science writing on the side) until earning a fellowship for an extended tour of research at Europe’s most prominent university chemistry laboratories.

When he returned to St. Petersburg, he had no job, so he wrote a masterful handbook on organic chemistry in hopes of winning a large cash prize. It was a long shot that paid off, with the lucrative Demidov Prize in 1862. He also found work as an editor, translator and consultant to various chemical industries. Eventually he returned to research, earning his Ph.D. in 1865 and then becoming a professor at the University of St. Petersburg.

Soon thereafter, Mendeleev found himself about to teach inorganic chemistry. In preparing to master that new (to him) field, he was unimpressed by the available textbooks. So he decided to write his own. Organizing the text required organizing the elements, so the question of how best to arrange them was on his mind.

By early 1869, Mendeleev had made enough progress to realize that some groups of similar elements showed a regular increase in atomic weights; other elements with roughly equal atomic weights shared common properties. It appeared that ordering the elements by their atomic weight was the key to categorizing them.

By Mendeleev’s own account, he structured his thinking by writing each of the 63 known elements’ properties on an individual note card. Then, by way of a sort of game of chemical solitaire, he found the pattern he was seeking. Arranging the cards in vertical columns from lower to higher atomic weights placed elements with similar properties in each horizontal row. Mendeleev’s periodic table was born. He sketched out his table on March 1, sent it to the printer and incorporated it into his soon-to-be-published textbook. He quickly prepared a paper to be presented to the Russian Chemical Society.


A handwritten draft of Mendeleev’s periodic table, in which he organized the elements by atomic weight to reveal the periodic law, showing how elements had similar properties at regular intervals, or periodicities.

150 years ago, the periodic table began with one chemist’s vision (3)

“Elements arranged according to the size of their atomic weights show clear periodic properties,” Mendeleev declared in his paper. “All the comparisons which I have made … lead me to conclude that the size of the atomic weight determines the nature of the elements.”

Meanwhile, the German chemist Lothar Meyer had also been working on organizing the elements. He prepared a table similar to Mendeleev’s, perhaps even before Mendeleev did. But Mendeleev published first.

More important than beating Meyer to the publication punch, though, was Mendeleev’s use of his table to make bold predictions about undiscovered elements. In preparing his table, Mendeleev had noticed that some note cards were missing. He had to leave blank spaces to get the known elements to properly align. Within his lifetime, three of those blanks were filled with the previously unknown elements gallium, scandium and germanium.

Not only had Mendeleev predicted the existence of these elements, but he had also correctly described their properties in detail. Gallium, for instance, discovered in 1875, had an atomic weight (as measured then) of 69.9 and a density six times that of water. Mendeleev had predicted an element (he called it eka-aluminum) with just that density and an atomic weight of 68. His predictions for eka-silicon closely matched germanium (discovered in 1886) in atomic weight (72 predicted, 72.3 observed) and density (5.5 versus 5.469). He also correctly predicted the density of germanium’s compounds with oxygen and chlorine.

Mendeleev’s table had become an oracle. It was as if end-of-game Scrabble tiles spelled out the secrets of the universe. While others had glimpsed the periodic law’s power, Mendeleev was the master at exploiting it.

Mendeleev’s successful predictions earned him legendary status as a maestro of chemical wizardry. But today, historians dispute whether the discovery of the predicted elements cemented the acceptance of his periodic law. The law’s approval may have been more due to its power to explain established chemical relationships. In any case, Mendeleev’s prognosticative accuracy certainly attracted attention to the merits of his table.

Elements arranged according to the size of their atomic weights show clear periodic properties.

—Dmitrii Mendeleev, 1869

By the 1890s, chemists widely recognized his law as a landmark in chemical knowledge. In 1900, the future Nobel chemistry laureate William Ramsay called it “the greatest generalization which has as yet been made in chemistry.” And Mendeleev had done it without understanding in any deep way why it worked at all.

A mathematical map

In many instances in the history of science, grand predictions based on novel equations have turned out to be correct. Somehow math reveals some of nature’s secrets before experimenters find them. Antimatter is one example, the expansion of the universe another. In Mendeleev’s case, the predictions of new elements emerged without any creative mathematics. But in fact, Mendeleev had discovered a deep mathematical map of nature, for his table reflected the implications of quantum mechanics, the mathematical rules governing atomic architecture.

In his textbook, Mendeleev had noted that “internal differences of the matter that comprises the atoms” could be responsible for the elements’ periodically recurring properties. But he did not pursue that line of thought. In fact, over the years he waffled about how important atomic theory was for his table.

But others could read the table’s message. In 1888, German chemist Johannes Wislicenus declared that the periodicity of the elements’ properties when arranged by weight indicated that atoms are composed of regular arrangements of smaller particles. So in a sense, Mendeleev’s table did anticipate (and provide evidence for) the complex internal structure of atoms, at a time when nobody had any idea what an atom really looked like, or even whether it had any internal structure at all.

By the time of Mendeleev’s death in 1907, scientists knew that atoms had parts: electrons, which carried a negative electric charge, plus some positively charged component to make atoms electrically neutral. A key clue to how those parts were arranged came in 1911, when the physicist Ernest Rutherford, working at the University of Manchester in England, discovered the atomic nucleus. Shortly thereafter Henry Moseley, a physicist who had worked with Rutherford, demonstrated that the amount of positive charge in the nucleus (the number of protons it contained, or its “atomic number”) determined the correct order of the elements in the periodic table.

Atomic weight was closely related to Moseley’s atomic number — close enough that ordering elements by weight differs in only a few spots from ordering by number. Mendeleev had insisted that those weights were wrong and needed to be remeasured, and in some cases he was right. A few discrepancies remained, but Moseley’s atomic number set the table straight.

At about the same time, the Danish physicist Niels Bohr realized that quantum theory governed the arrangement of electrons surrounding the nucleus and that the outermost electrons determined an element’s chemical properties.

150 years ago, the periodic table began with one chemist’s vision (4)

Similar arrangements of the outer electrons would recur periodically, explaining the patterns that Mendeleev’s table had originally revealed. Bohr created his own version of the table in 1922, based on experimental measurements of electron energies (along with some guidance from the periodic law).

Bohr’s table added elements discovered since 1869, but it was still, in essence, the periodic arrangement that Mendeleev had discovered. Without the slightest clue to quantum theory, Mendeleev had created a table reflecting the atomic architecture that quantum physics dictated.


In Danish physicist Niels Bohr’s 1922 version of the periodic table, adapted from a table by Danish chemist Julius Thomsen, elements with similar properties occupy horizontal rows connected by lines. The empty box on the right marks the expected occurrence of a group of elements that are chemically similar to the rare earth elements (numbers 58–70) in the preceding column.

150 years ago, the periodic table began with one chemist’s vision (5)

Bohr’s new table was neither the first nor last variant on Mendeleev’s original design. Hundreds of versions of the periodic table have been devised and published. The modern form, a horizontal design in contrast with Mendeleev’s original vertical version, became widely popular only after World War II, largely due to the work of the American chemist Glenn Seaborg (a longtime member of the board of Science Service, the original publisher of Science News).

Seaborg and collaborators had synthetically produced several new elements with atomic numbers beyond uranium, the last naturally occurring element in the table. Seaborg saw that these elements, the transuranics (plus the three elements preceding uranium) demanded a new row in the table, something Mendeleev had not foreseen. Seaborg’s table added the row for those elements beneath a similar row for the rare earth elements, whose proper place had never been quite clear, either. “It took a lot of guts to buck Mendeleev,” Seaborg, who died in 1999, said in a 1997 interview.

Seaborg’s contributions to chemistry earned him the honor of his own namesake element, seaborgium, number 106. It’s one of a handful of elements named to honor a famous scientist, a list that includes, of course, element 101, discovered by Seaborg and colleagues in 1955 and named mendelevium — for the chemist who above all others deserved a place at the periodic table.

150 years ago, the periodic table began with one chemist’s vision (6)
150 years ago, the periodic table began with one chemist’s vision (2024)


150 years ago, the periodic table began with one chemist’s vision? ›

And for chemistry, no cause for celebration surpasses the origin of the periodic table of the elements, created 150 years ago this March by the Russian chemist Dmitrii Ivanovich Mendeleev

Dmitri Mendeleev is often referred to as the Father of the Periodic Table. He called his table or matrix, "the Periodic System".
https://en.wikipedia.org › wiki › Dmitri_Mendeleev
. Mendeleev's table has become as familiar to chemistry students as spreadsheets are to accountants.

Who was the inventor of the periodic table reading answers with answers? ›

In 1869, Russian chemist Dmitri Mendeleev created the framework that became the modern periodic table, leaving gaps for elements that were yet to be discovered.

Why did chemist create the periodic table? ›

Q: How did it come about? A: Dmitri Mendeleev was writing a textbook when he came up with the idea. It was a scheme he put together in order to help organize the elements in families so that he didn't have to spend time doing each element individually.

What did the periodic table predict for scientists long ago? ›

Mendeleev's table predicted scandium, gallium, technetium, and germanium before any of these were isolated in a lab. Before Mendeleev, other chemists had organized other periodic tables, but these tables aren't used anymore because they were not predictive.

Who was the first chemist to define an element? ›

Antoine Laurent Lavoisier (1743-94), a French chemist, was the first to establish an experimentally useful definition of an element. He defined an element as a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Who was the first scientist to discover the periodic table? ›

The periodic table was invented by Russian chemist Dmitri Mendeleev in 1869. However, prior to Mendeleev, chemists had been pondering for decades how to classify the elements.

Who was the first person to use the periodic table? ›

Ask most chemists who discovered the periodic table and you will almost certainly get the answer Dmitri Mendeleev.

How did chemists discover elements? ›

Chemists also discovered new elements by looking at the light that substances gave off as they burned. Gustave Kirchoff and Robert Bunsen were German chemists. They used a prism to split the light coming from a burning object. Then they looked at the lines that were produced (called a spectrum).

How is the periodic table used by chemists? ›

Scientists use the periodic table to quickly refer to information about an element, like atomic mass and chemical symbol. The periodic table's arrangement also allows scientists to discern trends in element properties, including electronegativity, ionization energy, and atomic radius.

Who invented chemistry? ›

Lavoisier has been considered by many scholars to be the "father of chemistry". Chemists continued to discover new compounds in the 1800s. The science also began to develop a more theoretical foundation. John Dalton (1766-1844) put forth his atomic theory in 1807.

How did they predict the periodic table? ›

When Mendeleev proposed his periodic table, he noted gaps in the table and predicted that then-unknown elements existed with properties appropriate to fill those gaps. He named them eka-boron, eka-aluminium, eka-silicon, and eka-manganese, with respective atomic masses of 44, 68, 72, and 100.

What scientist was able to predict unknown elements using their own periodic table? ›

Mendeleev went even further. He corrected the known atomic masses of some elements and he used the patterns in his table to predict the properties of the elements he thought must exist but had yet to be discovered. He left blank spaces in his chart as placeholders to represent those unknown elements.

Who discovered each element? ›

Questions and Answers
Element NameDiscovered ByYear
HydrogenHenry Cavendish1766
IndiumFerdinand Reich Hieronymus Theodor Richter1863
IodineBarnard Courtois1811
IridiumSmithson Tennant1803
114 more rows

Which chemist discovered the most elements? ›

Albert Ghiorso (1915-2010) was an American nuclear scientist who co-discovered a world-record twelve elements on the periodic table. After receiving a B.S.

Why was the periodic table created? ›

Various forms of periodic table were constructed, notably by Antoine Lavoisier and John Newlands. The periodic table invented by Dmitri Mendeleev was significant because it was the first to enable determination of gaps in the elements and make predictions.

What element is named after a chemist? ›

Some of the best-known elements include einsteinium (Albert Einstein), curium (Marie and Pierre Curie), rutherfordium (Ernest Rutherford), nobelium (Alfred Nobel), and mendelevium (Dmitri Mendeleev).

Who created the periodic table quizlet? ›

In 1869, just five years after John Newlands put forward his Law of Octaves, a Russian chemist called Dmitri Mendeleev published a periodic table. Mendeleev also arranged the elements known at the time in order of relative atomic mass, but he did some other things that made his table much more successful.

Who invented the periodic table dream? ›

As one story has it, Mendeleev, exhausted from his three-day effort, fell asleep. He later recalled, “I saw in a dream, a table, where all the elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper.” (Strathern, 2000) He named his discovery the “periodic table of the elements.”

Who was known as the father of the periodic table? ›

Father of the Modern Periodic Table is Dmitri Mendeleev (published his periodic table in 1869). Dmitri Mendeleev laid the foundation of the modern periodic table. He organized elements into groups and rows according to their physical and chemical behaviour.

How did Dmitri Mendeleev contribute to the periodic table? ›

In 1869, Mendeleev contributed to the world of periodic tables by creating his version of the periodic table listing the most known elements at the time by their ascending atomic mass. The elements were also arranged by how reactive they were.

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