Carbon from antiquity Gold from antiquity Silver from antiquity Copper from antiquity Sulphur from antiquity Tin from antiquity Lead from antiquity Mercury from antiquity Iron from antiquity Arsenic Antimony - Bismuth 15th century?May have been described in writings attributed to Basil Valentinus
Phosphorus 1670 [Hennig Brandt]?, later described by Robert Boyle Cobalt 1732Platinum 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. 1750s Zinc Nickel Hydrogen Fluorine Nitrogen
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]?
Chlorine 1774 Karl Wilhelm Scheele Manganese 1780? Hjelm Molybdenum Tellurium 1782 [Mueller von Reichenstein]? Tungsten 1783
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 [M.H. Klaproth]?
Zirconium Strontium 1793 [M.H. Klaproth]? Titanium 1797 [M.H. Klaproth]? Yttrium Chromium Columbium? TantalumThe 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 [M.H. Klaproth]?; Jöns Jacob Berzelius and Hisinger
Rhodium Palladium Osmium Iridium MagnesiumAt this point, Humphrey 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 Humphrey Davy Calcium Sodium 1807 Humphrey Davy Barium 1808 Humphrey Davy Iodine Lithium 1817 Arfvedson(metal prepared by Bunsen using electrolysis in 1855) [This is unclear]
Cadmium 1817 [Friedrich Strohmeyer]?Independently discovered by K.S.L Hermann
Selenium 1817 Jöns Jacob Berzelius Silicon Aluminium 1825 Hans Christian Ørsted Bromine 1826 A.J. Balard Thorium Jöns Jacob Berzelius Beryllium 1828 Friedrich WöhlerIndependently discovered by A.A.B. Bussy
VanadiumThe next element discovered when Mosander showed that the cerium isolated in 1803 by Berzelius was actually a mixture of Cerium, Lanthanum and `Didymium' (didymium was not actually one element, and was resolved into two in 1885)
Lanthanum 1839-41 Mosander?
Terbium Erbium Ruthenium
Cesium 1860 Bunsen Rubidium 1860 Bunsen Thallium 1861 Sir William Crookes Indium 1863 Reich and RichterAnother 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
Boron 1868 [J.L. Gay-Lussac]? & L.J. Thenard
Gallium 1871 de Boisbaudran
Ytterbium Thulium 1879 P.T. Cleve Scandium 1879 Nilson Holmium Samarium Gadolinium
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 Germanium 1886 Winkler
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 Rayleigh & [Sir William Ramsay]?
Europium
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 Pierre and Marie Curie Polonium Pierre and Marie Curie Actinium 1899 A DebierneAnother 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 Pierre and Marie Curie
Lutetium Protactinium Hafnium Rhenium
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.
The elements labelled as "synthetic" are unstable, with a half-life 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 reactor]?s or [particle accelerator]?s.
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 Synthetic Francium
All subsequent elements after this are synthetic elements:
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 at Berkeley Plutonium 1941 Glenn T. Seaborg, Arthur C. Wahl, Joseph W. Kennedy Elilijo Segre Curium Americium Promethium Berkelium 1949 Stanley. Albert Ghiorso, Kennerth Stret Jnr, Glenn T. Seaborg Californium 1950 Stanley. Albert Ghiorso, Kennerth Stret Jnr, Glenn T. Seaborg Einsteinium Fermium Mendelevium 1955 Glenn T. Seaborg, Evans G. Valens Nobelium 1958 Lawrencium 1961 Rutherfordium 1964 Dubnium Seaborgium Bohrium Hassium Meitnerium
see also periodic table
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