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330 BC Greek philosopher and scientist Aristotle proposes four basic, pure elements that make up Earth: fire, air, water and earth
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360 BC Greek philosopher and mathematician Plato suggests the term ‘elements’ or stoicheia
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Democritus and Leucippus propose that all matter is made up of invisible particles called atoms
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1661 Irish chemist Robert Boyle publishes ‘The Sceptical Chymist’ containing information on modern atoms, molecules and chemical reactions
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1669 German merchant Hennig Brand attempts to make Philosopher’s Stone instead discovers phosphorus
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1754 Scottish chemist Joseph Black discovers carbon dioxide
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1766 British chemist Henry Cavendish discovers hydrogen
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1773 Swedish chemist Carl Wilhelm Scheele and English chemist Joseph Priestly discover oxygen
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1778 French chemist Antoine Lavoisier wrote first list of elements containing 33 elements categorised into metals and non-metals
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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
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1807 Cornish chemist Sir Humphry Davy discovers sodium then barium, strontium, calcium and magnesium
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1809 at least 47 elements are discovered, a pattern in characteristics is emerging
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1828 Swedish chemist Jakob Berzelius develops table of atomic weights, introduces letters to symbolise elements
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1828 German chemist Johann Dobereiner developed groups of 3 elements with similar properties called the ‘Law of Triads’
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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’
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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
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1869 Mendeleyev proposes the ‘Periodic Law’ by which “the elements arranged according to the magnitude of atomic weights show a periodic change of properties”
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1882 Thomas Bayley proposed a vertical version of the periodic table
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1886 French physicist Antoine Bequerel discovers radioactivity
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1894 Scottish chemist William Ramsay discovered the Noble Gases labelling it on the periodic table as group 0
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1895 French physicists Marie and Pierre Curie discover radium and polonium and that beta particles are negatively charged
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1895 German physicist Wilhelm Roentgen discovers the X-Ray that can travel through wood and flesh, showing an image of the internal body
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1897 English physicist J. J. Thomson discovered negatively charged particles called electrons
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1897 Irish physicist John Townsend and American physicist Robert Millikan measured electrons exact mass and electrical charge
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1898 New Zealand physicist Ernest Rutherford names three types of radiation; alpha, beta and gamma rays
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1905 A. Werner proposes a horizontal table
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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
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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
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1913 Danish physicist Niels Bohr recognises that electrons move around the nucleus in orbitals
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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
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1917 Rutherford is the first to split the atom "splitting the atom”
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1919 British chemist Francis William Aston discovered the existence of isotopes
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1932 English physicist James Chadwick discovers neutron, a neural atomic particle with a mass close to a proton
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1932 British physicist John Cockroft and the Irish physicist Ernest Walton, students under Rutherford, split a lithium atom
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1937 Italian mineralogist Carlo Perrier and Italian physicist Emilio Segrè are the first to create a synthetic element; technetium
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1940 American physicist Edwin McMillan discovers the first transuranium element, neptunium
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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
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1941 Seaborg, Arthur C. Wahl and Joseph W. Kennedy, produce plutonium, the second known transuranium element
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1945 Seaborg identified the lanthanides and actinides groups
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1997 International Union of Pure and Applied Chemistry officially name six new elements: Rutherfordium, Dubnium, Seaborgium, Bohrium, Hassium and Meitnerium
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2007 Theodore Gray creates a Photographic Periodic Table composed of photographic elements
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2010 Synthetic element 117 Unuseptium is created at the Joint Institute for Nuclear Research in Dubna
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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
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2014 UVS Periodic Table Model of a Klein Bottle Topology
