The Discoveries of the chemical elements reference article from the English Wikipedia on 24-Jul-2004
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Discoveries of the chemical elements

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The story of the discoveries of the chemical elements is presented here in chronological order. The elements are listed generally in the order in which they were first isolated as the pure element, rather than as a compound (some such as boron were known to be elements decades before they could be isolated from their compounds). The first few predate any written record.

Name Date Discoverer
Carbon antiquity
Gold antiquity
Silver antiquity
Copper antiquity
Sulphur antiquity
Tin antiquity
Lead antiquity
Mercury antiquity
Iron antiquity
Arsenic 1250 Albertus Magnus is believed to have been the first to isolate the element.
Antimony 1450 First described scientifically by Tholden
Zinc 1526 Identified as a unique metal by Paracelsus
Bismuth 15th century? May have been described in writings attributed to Basil Valentinus, definitively identified by Claude Geoffroy Junine in 1753
Phosphorus 1669 Hening Brand, later described by Robert Boyle
Cobalt 1732 George Brandt

Platinum had been noticed in South American gold ore since the 16th century. A number of chemists worked on platinum in the 18th century:

Platinum ca. 1741 Discovered independently by Antonio de Ulloa (published 1748) and Charles Wood.
Nickel 1751 Axel Frederik Cronstedt
Magnesium 1755 Joseph Black

Priestley's work on atmospheric gases resulted in his preparation of oxygen. As he was a believer in phlogiston, he didn't realise that he had prepared a new element, and thought that he had managed to prepare air free from phlogiston ("de-phlogisticated air"). However, he was the first to isolate oxygen, even if he didn't realise what he had:

Oxygen 1771 Joseph Priestley
Nitrogen 1772 Daniel Rutherford
Chlorine 1774 Karl Wilhelm Scheele
Manganese 1774 J. G. Gahn
Hydrogen 1776 Isolated and described by Henry Cavendish, named by Antoine Lavoisier
Molybdenum 1778 Carl Wilhelm Scheele
Tellurium 1782 Mueller von Reichenstein
Tungsten 1783 José Elhuyar and Fausto Elhuyar

The recent discovery of the new planet Uranus by William Herschel had caused a stir, so the newly discovered metallic element was christened uranium in its honour.

Uranium 1789 Martin Heinrich Klaproth
Zirconium 1789 Martin Heinrich Klaproth
Strontium 1793 Martin Heinrich Klaproth
Yttrium 1794 Johann Gadolin
Titanium 1797 Martin Heinrich Klaproth
Chromium 1797 Nicolas-Louis Vauquelin
Beryllium 1798 Nicolas-Louis Vauquelin
Vanadium 1801 Andres Manuel del Rio
Columbium 1801 Charles Hatchett
Tantalum 1802 Anders Ekeberg

The next element was discovered just after the discovery of a new class of astronomical objects: the new element was named after the newly discovered asteroid, Ceres. The element was discovered nearly simultaneously in two laboratories, though it was later shown that Berzelius and Hisinger's cerium was actually a mixture of cerium, lanthanum and didymium.

Cerium 1803 Martin Heinrich Klaproth; Jöns Jacob Berzelius and Hisinger
Rhodium 1803 William Hyde Wollaston
Palladium 1803 William Hyde Wollaston
Osmium 1803 Smithson Tennant
Iridium 1803 Smithson Tennant

At this point, Sir Humphry Davy pioneered the use of electricity from the Voltaic pile to decompose the salts of alkali metals, and so a number of thse metals were first prepared as the pure element: the beginning of the field of electrochemistry.

Potassium 1807 Humphry Davy
Sodium 1807 Humphry Davy
Calcium 1808 Humphry Davy
Barium 1808 Humphry Davy
Iodine 1811 Bernard Courtois
Lithium 1817 Johann Arfvedson
Cadmium 1817 Friedrich Strohmeyer Independently discovered by K.S.L Hermann
Selenium 1817 Jöns Jacob Berzelius
Silicon 1823 Jöns Jacob Berzelius
Aluminium 1825 Hans Christian Ørsted
Bromine 1826 Antoine Jerome Balard
Thorium 1828 Jöns Jacob Berzelius
Beryllium 1828 Friedrich Wöhler Independently discovered by A.A.B. Bussy

The next element discovered when Mosander showed that the cerium isolated in 1803 by Berzelius was actually a mixture of cerium, lanthanum and so-called didymium (which was not actually one element, and was resolved into two in 1885).

Lanthanum 1839-41 Carl Mosander
Terbium 1843 Carl Mosander
Erbium 1843 Carl Mosander
Ruthenium 1844 Karl Klaus

Spectroscopic discoveries

A number of elements were first identified by their spectroscopic emission lines: caesium and rubidium were discovered by Bunsen and Kirchhoff analysing the spectrum of alkali salts. The unknown element with blue emission lines was named caesium; in purifying the salts of this new element, another element was discovered with a red emission line; this was called rubidium.. They were shortly afterwards prepared as the pure salts by Bunsen. The bright green line of thallium caused it to be named from the Greek thallos, meaning a green shoot, and the indigo-blue line from certain specimens of zinc-blende gave the name indium to the new element so discovered:

Caesium 1860 Bunsen
Rubidium 1860 Bunsen
Thallium 1861 Sir William Crookes
Indium 1863 Ferdinand Reich and Theodor Richter

Another spectroscopic discovery, helium was found by astronomers as an emission line in the spectrum of the sun, hence its name from the Greek helios meaning sun. It was at first thought to be an unknown metallic element, and so the name was given the ending -ium to signify a metal. By the time it had been found on Earth and discovered to be the lightest of the noble gases, the name was fixed; by analogy with the other noble gases, the name should have ended in -on.

Helium 1868 Independently by Pierre Janssen and Norman Lockyer
Boron 1868 Joseph Louis Gay-Lussac & L.J. Thenard

The Periodic table and the prediction of new elements

In 1871, Mendeleev predicted, from the gaps in his newly-devised periodic table, that there should be three as yet undiscovered elements, which he named eka-boron, eka-aluminium, and eka-silicon. With Mendeleev's prediction of their existence and approximate chemical properties, the missing elements were found by French, Scandinavian, and German chemists, and named for their countries of discovery, as gallium, scandium, and germanium:

Gallium 1875 Paul Émile Lecoq de Boisbaudran
Ytterbium 1878 Jean Charles Galissard de Marignac
Thulium 1879 Per Teodor Cleve
Scandium 1879 Lars Fredrick Nilson
Holmium 1879 Marc Delafontaine & Jacques Louis Soret
Samarium 1879 Paul Émile Lecoq de Boisbaudran
Gadolinium 1880 Jean Charles Galissard de Marignac

The 'didymium' isolated by Mosander in 1839 was shown to actually be two separate elements, praseodymium and neodymium:

Praseodymium 1885 Carl Auer von Welsbach
Neodymium 1885 Carl Auer von Welsbach
Dysprosium 1886 Paul Emile Lecoq de Boisbaudran
Germanium 1886 Clemens Winkler
Fluorine 1886 Joseph Henri Moissan

Refrigeration technology advanced considerably during the 19th century, to the point where it was possible to liquefy atmospheric gases. A curious observation was made: Nitrogen prepared by chemical means from its compounds had a slightly lower molecular weight than nitrogen prepared by liquefaction from air. This was attributed as being due to the presence of a previously unsuspected gas, christened argon. This gas was the first representative found of a previously unsuspected new group in the periodic table, first known as the inert gases, now more commonly known as the noble gases.

Argon 1894 Lord Rayleigh & Sir William Ramsay

Once liquid argon could be prepared in quantity from air, small amounts of a further three noble gases could be separated from it by differences in boiling point. These new elements were named from the Greek words for, respectively, 'new', 'hidden', and 'foreign'.

Neon 1898 Sir William Ramsay
Krypton 1898 Sir William Ramsay
Xenon 1898 Sir William Ramsay

With the discovery of radioactivity, we have the classic work by the Curies that isolated a number of previously unknown elements:

Radium 1898 Pierre Curie and Marie Curie
Polonium 1898 Pierre Curie and Marie Curie

Another of the noble gases, radon had avoided discovery because its short radioactive half-life had meant it was present in air in vanishingly tiny quantities. Once radium was available in macroscopic quantities, the production of this radioactive noble gas was readily detected as a product of radium's radioactive decay.

Radon 1898 Fredrich Ernst Dorn who called it nitron
Actinium 1899 André-Louis Debierne
Europium 1901 Eugene Demarcay
Lutetium 1907 Georges Urbain
Protactinium 1917 Kasimir Fajans, O. Göhring, Fredrich Soddy, John Cranston, Lise Meitner and Otto Hahn
Hafnium 1923 Dirk Coster
Rhenium 1925 Walter Noddack and Ida Tacke

At this point, all the stable elements existing on earth had been discovered, and most of the periodic table had been filled. A few gaps remained amongst the higher mass elements, but there remained a troublesome gap at element number 43, just below manganese in the table. The gaps were filled by the synthetic elements. Walter Noddack and Ida Tacke (later Ida Noddack) also believed to have found Technetium, which they called Masurium (after Masurien, an area in Germany). They were later proved wrong.

The synthetic elements

The so-called "synthetic" elements are unstable, with half-lives so "short" relative to the age of the earth that any atoms of that element that may have been present when the earth formed have long since completely decayed away. Hence they are only known on earth as the product of nuclear reactors, particle accelerators, or in the byproducts from nuclear explosions. The discovery of technetium finally filled in a puzzling gap in the periodic table, and the discovery that there were no stable isotopes of technetium explained its absence on earth: its 4.2 million years half-life meant that none remained from the time of formation of the earth.

Technetium 1937 Carlo Perrier
Francium (natural) 1939 Marguerite Derey

All elements after this are synthetic:

Astatine 1940 Dale R. Corson, K.R.Mackenzie, Emilio Segre'

The next two elements were the first of the transuranic (beyond uranium) elements and were named after the planets beyond Uranus, Neptune and Pluto:

Neptunium 1940 E.M. McMillan & Philip H. Abelson, University of California, Berkeley
Plutonium 1941 Glenn T. Seaborg, Arthur C. Wahl, Joseph W. Kennedy Emilio Segré
Curium 1944 Glenn T. Seaborg
Americium 1945 Glenn T. Seaborg
Promethium 1945 J.A. Marinsky
Berkelium 1949 Albert Ghiorso, Glenn T. Seaborg, Stanley G. Thompson, Kenneth Street Jr
Californium 1950 Albert Ghiorso, Glenn T. Seaborg, Stanley G. Thompson, Kenneth Street Jr
Einsteinium 1952 Argonne Laboratory, Los Alamos Laboratory, and University of California
Fermium 1953 Argonne Laboratory, Los Alamos Laboratory, and University of California
Mendelevium 1955 Glenn T. Seaborg, Evans G. Valens
Nobelium 1958 Albert Ghiorso, Glenn T. Seaborg, John R. Walton and Torbørn Sikkeland
Lawrencium 1961 Albert Ghiorso, Torbjorn Sikkeland, Almon Larsh and Robert M. Latimer
Rutherfordium 1964 Joint Nuclear Research Institute at Dubna, U.S.S.R.
Dubnium 1970 Albert Ghiorso
Seaborgium 1974 Joint Nuclear Research Institute and University of California, Berkeley
Bohrium 1976 Y. Oganessian et al, Dubna and confirmed at GSI (1982)
Meitnerium 1982 Peter Armbruster and Gottfried Münzenberg, GSI
Hassium 1984 Peter Armbruster and Gottfried Münzenberg
Darmstadtium 1994 S. Hofmann, V. Ninov et al, GSI
Unununium 1994 S. Hofmann, V. Ninov et al, GSI
Ununbium 1996 S. Hofmann, V. Ninov et al, GSI
Ununquadium 1999 Joint Nuclear Research Institute at Dubna
Ununtrium 2004 Joint Nuclear Research Institute at Dubna and Lawrence Livermore National Laboratory
Ununpentium 2004 Joint Nuclear Research Institute at Dubna and Lawrence Livermore National Laboratory

See also