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330
Aristotle
330 BC Greek philosopher and scientist Aristotle proposes four basic, pure elements that make up Earth: fire, air, water and earth -
Period: 330 to 440
BC
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360
Plato
360 BC Greek philosopher and mathematician Plato suggests the term ‘elements’ or stoicheia -
440
Democritus and Leucippus
Democritus and Leucippus propose that all matter is made up of invisible particles called atoms -
Robert Boyle
1661 Irish chemist Robert Boyle publishes ‘The Sceptical Chymist’ containing information on modern atoms, molecules and chemical reactions -
Hennig Brand
1669 German merchant Hennig Brand attempts to make Philosopher’s Stone instead discovers phosphorus -
Joseph Black
1754 Scottish chemist Joseph Black discovers carbon dioxide -
Henry Cavendish
1766 British chemist Henry Cavendish discovers hydrogen -
Scheele and Priestly
1773 Swedish chemist Carl Wilhelm Scheele and English chemist Joseph Priestly discover oxygen -
Antoine Lavoisier
1778 French chemist Antoine Lavoisier wrote first list of elements containing 33 elements categorised into metals and non-metals -
John Dalton
1803 English chemist John Dalton proposed “Dalton's Atomic Theory” stating atoms are indivisible and differ in size, shape, mass, position and arrangement depending on physical state and element of object -
Sir Humphry Davy
1807 Cornish chemist Sir Humphry Davy discovers sodium then barium, strontium, calcium and magnesium -
Update
1809 at least 47 elements are discovered, a pattern in characteristics is emerging -
Jakob Berzelius
1828 Swedish chemist Jakob Berzelius develops table of atomic weights, introduces letters to symbolise elements -
Johann Dobereiner
1828 German chemist Johann Dobereiner developed groups of 3 elements with similar properties called the ‘Law of Triads’ -
John Newlands
1864 English chemist John Newlands arranged 56 known elements into 11 groups elements in order of atomic weights and characteristics, putting forward his ‘Law of Octaves’ -
Dmitri Mendeleev
1869 Russian chemist Dmitri Mendeleev uses the 66 known elements to create his famous table, including 7 groups horizontally arranged by atomic weights and set in vertical columns with similar characteristics -
Dmitri Mendeleyev
1869 Mendeleyev proposes the ‘Periodic Law’ by which “the elements arranged according to the magnitude of atomic weights show a periodic change of properties” -
Thomas Bayley
1882 Thomas Bayley proposed a vertical version of the periodic table -
Antoine Bequerel
1886 French physicist Antoine Bequerel discovers radioactivity -
William Ramsay
1894 Scottish chemist William Ramsay discovered the Noble Gases labelling it on the periodic table as group 0 -
Marie and Pierre Curie
1895 French physicists Marie and Pierre Curie discover radium and polonium and that beta particles are negatively charged -
Wilhelm Roentgen
1895 German physicist Wilhelm Roentgen discovers the X-Ray that can travel through wood and flesh, showing an image of the internal body -
J. J. Thomson
1897 English physicist J. J. Thomson discovered negatively charged particles called electrons -
Townsend and Millikan
1897 Irish physicist John Townsend and American physicist Robert Millikan measured electrons exact mass and electrical charge -
Ernest Rutherford
1898 New Zealand physicist Ernest Rutherford names three types of radiation; alpha, beta and gamma rays -
A. Werner
1905 A. Werner proposes a horizontal table -
Rutherford and Geiger
1911 Rutherford and German physicist Hans Geiger discovers that electrons orbit the nucleus of an atom, and established that the nucleus was dense, small and positively charged -
Henry Moseley
1913 English physicist Henry Moseley determined the atomic numbers of the elements, stating "The atomic number of an element is equal to the number of protons in the nucleus”, his contribution altered the periodic table by reorganising it based on the atomic number instead of the atomic mass -
Niels Bohr
1913 Danish physicist Niels Bohr recognises that electrons move around the nucleus in orbitals -
Rutherford
1914 Rutherford identified the positive charge in the nucleus was due to protons, he was also the first to convert a nitrogen atom into an oxygen atom -
Rutherford
1917 Rutherford is the first to split the atom "splitting the atom” -
Francis Aston
1919 British chemist Francis William Aston discovered the existence of isotopes -
James Chadwick
1932 English physicist James Chadwick discovers neutron, a neural atomic particle with a mass close to a proton -
Cockroft and Walton,
1932 British physicist John Cockroft and the Irish physicist Ernest Walton, students under Rutherford, split a lithium atom -
Perrier and Segrè
1937 Italian mineralogist Carlo Perrier and Italian physicist Emilio Segrè are the first to create a synthetic element; technetium -
Edwin McMillan
1940 American physicist Edwin McMillan discovers the first transuranium element, neptunium -
Glenn Seaborg
1940 American scientist Glenn Seaborg synthesised 6 transuranic elements (after uranium in the periodic table) suggesting a change in the layout of the periodic table -
Seaborg, Wahl and Kennedy
1941 Seaborg, Arthur C. Wahl and Joseph W. Kennedy, produce plutonium, the second known transuranium element -
Seaborg
1945 Seaborg identified the lanthanides and actinides groups -
International Union of Pure and Applied Chemistry
1997 International Union of Pure and Applied Chemistry officially name six new elements: Rutherfordium, Dubnium, Seaborgium, Bohrium, Hassium and Meitnerium -
Theodore Gray
2007 Theodore Gray creates a Photographic Periodic Table composed of photographic elements -
Institute for Nuclear Research
2010 Synthetic element 117 Unuseptium is created at the Joint Institute for Nuclear Research in Dubna -
GSI Helmholtz Centre
1994 Man-made “superheavy” transuranium elements are created in the labs of GSI Helmholtz Centre for Heavy Ion Research, including element 110: Darmstadtium, element 111: Roentgenium and element 112: Copernicium -
Universal Vortical Singularity
2014 UVS Periodic Table Model of a Klein Bottle Topology
