Timeline of the Periodic Table
The discovery of the chemical elements and the growth of the periodic table, from copper smelting around 5000 BCE and the Greek four elements through Lavoisier and Mendeleev to the naming of oganesson in 2016.
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- 32 events ~5000 BCE – 2016
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- by claude-opus-5-5
~5000 BCE: Smelters extract copper from its ores
Finds at Belovode in Serbia are among the oldest securely dated evidence of copper smelting, after millennia in which people had hammered native copper. By the end of antiquity seven metals were known (gold, silver, copper, tin, lead, iron and mercury), as were carbon and sulfur, though no one yet thought of them as elements in the modern sense.
https://en.wikipedia.org/wiki/Metals_of_antiquity~450 BCE: Empedocles proposes four roots of all matter
The Greek philosopher Empedocles of Acragas in Sicily taught that everything is made of four "roots" (earth, water, air and fire), mixed and separated by the forces of Love and Strife. Plato called them stoicheia, "elements", and Aristotle added a fifth, aether, for the heavens; Indian philosophy had a similar set of five. The scheme remained standard in European thought until it was challenged in the 17th century.
https://en.wikipedia.org/wiki/Classical_element9th century: Arabic alchemists derive metals from sulfur and mercury
The theory that metals form in the earth from two principles, an idealized sulfur (combustibility) and mercury (metallic character), appeared first in "The Secret of Creation", an Arabic work attributed to Apollonius of Tyana and dated to the late 8th or early 9th century. Writings attributed to Jabir ibn Hayyan, which most scholars date to about 850 – 950, developed it, and it underlay theories of metals in the Islamic world and Europe until the 18th century.
https://en.wikipedia.org/wiki/Jabir_ibn_Hayyan#The_sulfur–mercury_theory_of_metals1661: Boyle challenges the four elements and three principles
In "The Sceptical Chymist", a dialogue, Robert Boyle argued that neither Aristotle's four elements nor the three principles of Paracelsus (salt, sulfur and mercury) had been shown by experiment, since heating a substance did not simply separate its ingredients. He defined elements as "perfectly unmingled bodies" from which mixtures are made, but doubted that any known substance was one, and favored a theory of particles, or corpuscles.
https://en.wikipedia.org/wiki/The_Sceptical_Chymist1669: Brand isolates phosphorus from urine
Searching for the philosopher's stone, the Hamburg alchemist Hennig Brand boiled down urine and heated the residue until a waxy white substance distilled over that glowed in the dark; he named it phosphorus, "light-bearer". It is usually counted as the first element discovered by a known person rather than known since antiquity. Brand kept his method secret, but Johann Kunckel and Robert Boyle reproduced it by 1680.
https://en.wikipedia.org/wiki/Hennig_Brand1766: Cavendish identifies inflammable air, later named hydrogen
In a paper to the Royal Society on "factitious airs", Henry Cavendish showed that the gas given off when metals dissolve in acids was a distinct substance, measured its density and called it "inflammable air". Others, including Robert Boyle in 1671, had produced it without recognizing it as distinct. Cavendish found in 1781 that it burns to form water, and Antoine Lavoisier named it hydrogen, "water-former".
https://en.wikipedia.org/wiki/Hydrogen#18th_century1774: Scheele and Priestley isolate oxygen
On August 1, Joseph Priestley in England focused sunlight on mercuric oxide and collected a gas in which a candle burned brightly, which he called "dephlogisticated air". Carl Wilhelm Scheele in Sweden had made the same gas around 1771 – 1772 but did not publish until 1777. Antoine Lavoisier, whom Priestley told of his experiment in Paris that October, recognized it as an element, named it oxygen and used it to overturn the phlogiston theory of combustion.
https://en.wikipedia.org/wiki/Oxygen#Scientific_era1789: Lavoisier's textbook lists 33 simple substances
Antoine Lavoisier's "Traité élémentaire de chimie" (Elementary Treatise on Chemistry) treated as elements the substances that chemical analysis had not broken down and listed 33 of them. Twenty-three are elements in the modern sense; the rest included light, caloric (heat), the radicals of acids whose elements were still unknown, and five "earths" later shown to be oxides. The book won a younger generation of chemists over to his oxygen-based chemistry.
https://en.wikipedia.org/wiki/Trait%C3%A9_%C3%89l%C3%A9mentaire_de_Chimie1807: Davy isolates potassium and sodium by electrolysis
Using large voltaic batteries at the Royal Institution in London, Humphry Davy passed electric current through caustic potash and caustic soda and obtained two new, highly reactive metals, potassium and sodium. In 1808, adopting a mercury-cathode method reported to him by Jöns Jacob Berzelius, he obtained calcium, strontium, barium and magnesium, showing that the alkaline "earths" were compounds of metals with oxygen.
https://en.wikipedia.org/wiki/Humphry_Davy#Potassium_and_sodium1808: Dalton assigns relative weights to atoms
In "A New System of Chemical Philosophy", John Dalton argued that each element consists of identical atoms of a characteristic weight and that compounds form when atoms combine in simple whole-number ratios. He gave weights relative to hydrogen as 1, extending a short list he had presented in 1803, but by assuming the simplest formulas, such as HO for water, he put oxygen at 7 instead of about 16.
https://en.wikipedia.org/wiki/John_Dalton#Atomic_theory1813 – 1814: Berzelius introduces letter symbols for the elements
In an essay published in five parts, Jöns Jacob Berzelius proposed writing each element as a one- or two-letter abbreviation of its Latin name, such as O for oxygen and Fe for iron, with numbers for proportions in compounds, and ended with a table of atomic weights on a scale with oxygen at 100. His numbers were superscripts, later replaced by subscripts; he refined weights for nearly all known elements through 1826.
https://en.wikipedia.org/wiki/J%C3%B6ns_Jacob_Berzelius#Chemical_notation1829: Döbereiner groups similar elements into triads
Johann Wolfgang Döbereiner, a professor at Jena, reported groups of three chemically similar elements, such as calcium, strontium and barium or chlorine, bromine and iodine, in which the middle member's atomic weight was close to the average of the other two. He had noticed the pattern for the alkaline earths in 1817. Many elements fit no triad, but the idea suggested that properties were linked to atomic weight.
https://en.wikipedia.org/wiki/D%C3%B6bereiner%27s_triads1860: Bunsen and Kirchhoff find cesium by spectroscopy
Robert Bunsen and Gustav Kirchhoff in Heidelberg, who had begun analyzing the light of flames with a prism spectroscope in 1859, saw unknown blue lines in the spectrum of mineral water from Dürkheim and named the new element cesium, from the Latin for bluish gray; rubidium, named for its red lines, followed in 1861. Spectroscopy could detect elements present only in traces and soon revealed thallium, indium and, in the Sun, helium.
https://en.wikipedia.org/wiki/Caesium#History1860: Karlsruhe Congress takes up atomic weights
About 140 chemists met at Karlsruhe, Germany, on September 3 – 5 for the first international chemistry conference, called by August Kekulé, Adolphe Wurtz and Karl Weltzien to settle disputes over atoms, molecules and atomic weights. It reached no firm agreement, but Stanislao Cannizzaro's 1858 paper, handed out at the close, showed how Amedeo Avogadro's 1811 hypothesis gave consistent atomic weights. Lothar Meyer and Dmitri Mendeleev both attended.
https://en.wikipedia.org/wiki/Karlsruhe_Congress1862 – 1866: Chancourtois and Newlands find a periodic pattern
The French geologist Alexandre-Émile Béguyer de Chancourtois arranged the elements by atomic weight on a spiral around a cylinder, his "telluric screw", so that similar elements lined up vertically, but his papers to the Academy of Sciences appeared without the diagram. In London, John Newlands proposed in 1865 a "law of octaves", in which every eighth element resembles the first; when he presented it in 1866, the Chemical Society declined to publish it.
https://en.wikipedia.org/wiki/History_of_the_periodic_table#Comprehensive_formalizations1869: Mendeleev publishes his periodic system
While writing a textbook, Dmitri Mendeleev in Saint Petersburg arranged the 63 elements then known by atomic weight so that chemically similar ones fell into groups, sent printed copies to chemists and published the table through the Russian Chemical Society. He left gaps for undiscovered elements and revised several accepted atomic weights, such as uranium's, and in 1870 – 1871 predicted the properties of "eka-aluminum", "eka-boron" and "eka-silicon" in detail. Lothar Meyer published a similar table in 1870, largely independently.
https://en.wikipedia.org/wiki/Dmitri_Mendeleev#Periodic_table1875: Lecoq de Boisbaudran discovers gallium
Examining zinc blende with a spectroscope, the French chemist Paul-Émile Lecoq de Boisbaudran, unaware of any prediction, found two unfamiliar violet lines, obtained the metal by electrolysis and named it gallium, from Gallia, Latin for France. Mendeleev identified it as his predicted eka-aluminum and argued that its density should be about 5.9 grams per cubic centimeter rather than the reported 4.7; remeasurement gave 5.9, the first confirmation of a prediction from the table.
https://en.wikipedia.org/wiki/Gallium#History1886: Winkler discovers germanium, Mendeleev's eka-silicon
Analyzing argyrodite, a new silver mineral from a mine near Freiberg in Saxony, Clemens Winkler found that its known components did not account for all of its weight and, after months of work, isolated a new element that he named germanium. Its atomic weight of about 72.3 and the properties of its compounds closely matched Mendeleev's eka-silicon; with gallium and Lars Fredrik Nilson's scandium (eka-boron, 1879), it helped win acceptance for the periodic table.
https://en.wikipedia.org/wiki/Germanium#History1894 – 1898: Argon and the other noble gases discovered
Lord Rayleigh found that nitrogen taken from air was slightly denser than nitrogen made from compounds; with William Ramsay he traced the difference to argon, an unreactive gas that fit no group in Mendeleev's table. Ramsay found helium, known since 1868 only from a line in the Sun's spectrum, in a uranium mineral in 1895, and with Morris Travers isolated neon, krypton and xenon in 1898. The gases became a new group; Rayleigh and Ramsay received Nobel Prizes in 1904.
https://en.wikipedia.org/wiki/Noble_gas#History1898: The Curies discover polonium and radium
Splitting pitchblende into fractions and testing each for radioactivity, a word Marie Curie coined, Marie and Pierre Curie reported polonium in July, the first element identified by its radioactivity alone, and radium in December. Marie Curie and André-Louis Debierne isolated radium metal in 1910, and she received the 1911 Nobel Prize in Chemistry for the two discoveries.
https://en.wikipedia.org/wiki/Radium#History1913: Soddy proposes isotopes, atoms sharing one place
Radioactive decay chains had yielded about 40 apparently distinct "radioelements" between uranium and lead, where the table had only 11 places. Frederick Soddy and Kazimierz Fajans independently showed how alpha and beta decay shift an element's position, and Soddy concluded that chemically identical atoms of different weight share one place, naming them isotopes, Greek for "same place", at the suggestion of the Scottish physician Margaret Todd. J. J. Thomson found two kinds of neon atom, the first sign of isotopes in a stable element.
https://en.wikipedia.org/wiki/Isotope#History1913: Moseley ties the table to atomic number
Measuring the X-rays emitted by metals, Henry Moseley found that the square root of their frequency rose in regular steps from one element to the next, giving physical meaning to atomic number, the nuclear charge that Antonius van den Broek had proposed as an element's place. Ordering by atomic number instead of weight settled anomalies such as cobalt and nickel and showed that elements 43, 61, 72 and 75 were missing between aluminum and gold. Moseley was killed at Gallipoli in 1915.
https://en.wikipedia.org/wiki/Moseley%27s_law1923: Coster and Hevesy find hafnium in zirconium ores
Electron-shell arguments by Charles Bury in 1921 and by Niels Bohr implied that element 72 should resemble zirconium rather than the rare earths, among which Georges Urbain claimed to have found it as "celtium". At Bohr's institute in Copenhagen, Dirk Coster and George de Hevesy detected its X-ray lines in zirconium minerals, reported it in Nature in January and named it hafnium, after Hafnia, Latin for Copenhagen. With rhenium, found in 1925, it was one of the last two stable elements discovered.
https://en.wikipedia.org/wiki/Hafnium#History1937: Perrier and Segrè identify element 43, technetium
Emilio Segrè, visiting Berkeley in 1936, persuaded Ernest Lawrence to send him a radioactive molybdenum foil from the deflector of his cyclotron. At the University of Palermo, Segrè and Carlo Perrier showed chemically that it contained element 43, the first element identified in artificially produced material; it was named technetium, from the Greek for "artificial", in 1947. Earlier claims, including "masurium" in 1925, could not be reproduced.
https://en.wikipedia.org/wiki/Technetium#Official_discovery_and_later_history1939: Perey discovers francium in the decay of actinium
Marguerite Perey, who had joined Marie Curie's Radium Institute in Paris as a laboratory assistant, noticed unexpected radiation from purified actinium and in January identified element 87, a short-lived product of its alpha decay, later named francium after her country. It was the last element discovered in nature rather than first made artificially; astatine, element 85, was synthesized at Berkeley in 1940.
https://en.wikipedia.org/wiki/Francium#Perey's_analysis1940: McMillan and Abelson make neptunium, element 93
At the Radiation Laboratory in Berkeley, Edwin McMillan and Philip Abelson showed that uranium-239, made when uranium captures a neutron, beta-decays into element 93, the first transuranium element, named neptunium after the planet beyond Uranus. Glenn Seaborg's team made element 94, plutonium, in late 1940 and early 1941, a result kept secret until 1946; McMillan and Seaborg shared the 1951 Nobel Prize in Chemistry.
https://en.wikipedia.org/wiki/Neptunium#Discovery1945: Seaborg moves the actinides below the lanthanides
Elements from actinium on had been placed as a fourth row of transition metals, an assumption that frustrated searches for elements 95 and 96. Glenn Seaborg, working on the Manhattan Project, proposed to colleagues in 1944 that they form a second series like the lanthanides, filling 5f orbitals; treating them that way let his team identify americium and curium. Published in 1945, the actinide concept gave the table its familiar separate row of actinides beneath the lanthanides.
https://en.wikipedia.org/wiki/Actinide_concept1955: Berkeley team makes mendelevium one atom at a time
Albert Ghiorso, Bernard Harvey, Gregory Choppin, Stanley Thompson and Glenn Seaborg bombarded a target of about a billion einsteinium atoms with alpha particles in a Berkeley cyclotron and identified element 101 from atoms detected one at a time, establishing techniques for identifying new elements from just a few atoms. They named it mendelevium after Dmitri Mendeleev, a tribute to a Russian that, during the Cold War, needed approval from the United States government.
https://en.wikipedia.org/wiki/Mendelevium1997: Chemists settle names for elements 104 to 109
Laboratories in Berkeley and in Dubna, Soviet Union (later Russia), had disputed credit and names for elements 104 to 106 since the 1960s, and a 1994 compromise by the International Union of Pure and Applied Chemistry (IUPAC) drew protests. Its general assembly in Geneva adopted rutherfordium, dubnium, seaborgium, bohrium, hassium and meitnerium, ending the "Transfermium Wars"; seaborgium became the first element named for a person then living.
https://en.wikipedia.org/wiki/Transfermium_Wars2004: RIKEN team in Japan makes element 113
On July 23, Kosuke Morita's group at the RIKEN institute in Wakō, Japan, detected a single atom of element 113, made by firing zinc-70 ions at a bismuth-209 target for nearly a year. A second atom followed in April 2005 and a decisive third, whose decay chain ran through known isotopes, in August 2012. On that evidence the element was credited to RIKEN in 2015, the first new element credited to an Asian research institute, and named nihonium, from Nihon, Japan.
https://en.wikipedia.org/wiki/Nihonium#Riken2015: Elements 113, 115, 117 and 118 confirmed
On December 30, the International Union of Pure and Applied Chemistry (IUPAC) announced that a joint working party with the International Union of Pure and Applied Physics had verified four discoveries, completing the seventh row of the periodic table. Element 113 went to RIKEN in Japan; 115 and 117 to the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, with the Lawrence Livermore and Oak Ridge national laboratories in the United States; and 118, reported in 2006 from atoms made by firing calcium-48 ions at californium, to JINR and Livermore.
https://en.wikipedia.org/wiki/Superheavy_element#Discoveries2016: Nihonium, moscovium, tennessine and oganesson named
On November 28, after a five-month public review, the International Union of Pure and Applied Chemistry (IUPAC) approved names for elements 113, 115, 117 and 118: nihonium (Nh) for Japan, moscovium (Mc) for the Moscow region, tennessine (Ts) for Tennessee and oganesson (Og) for the Russian physicist Yuri Oganessian, a leader in making the heaviest elements. Oganesson, which closes the seventh row, was the second element after seaborgium named for a living person.
https://en.wikipedia.org/wiki/Oganesson#Naming