The discovery of the chemical elements, in chronological order. These are listed generally in the order in which they were first isolated as the pure element, rather than as a compound (it was known that 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.
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 1732
Platinum had been noticed in South American gold ore since the 16th century, a number of chemists worked on Platinum in the 18th century:
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:
Chlorine 1774 Karl Wilhelm Scheele Manganese 1780? Hjelm Molybdenum Tellurium 1782 Mueller von Reichenstein Tungsten 1783
Zirconium Strontium 1793 M.H. Klaproth Titanium 1797 M.H. Klaproth Yttrium Chromium Columbium Tantalum
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 M.H. Klaproth; Jöns Jacob Berzelius and Hisinger
At 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]
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 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 `Didymium' (didymium was not actually one element, and was resolved into two in 1885)
A number of elements were first identified by their spectroscopic emission lines: Cesium and Rubidium were discovered by Bunsen and Kirchhoff analysing the spectrum of alkali salts. The unknown element with blue emission lines was named caesium (later cesium); 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:
Cesium 1860 Bunsen Rubidium 1860 Bunsen Thallium 1861 Sir William Crookes Indium 1863 Reich and 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
Boron 1868 J.L. 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:
The 'didymium' isolated by Mosander in 1839 was shown to actually be two separate elements, praseodymium and neodymium:
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
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'
With the discovery of Radioactivity, we have the classic work by the Curies that isolated a number of previously unknown elements:
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.
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 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 reactors or particle accelerators.
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'
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