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Periodic trend

Year Discovered

When each element was first isolated or identified. Elements known since antiquity are excluded from the plot.

Year Discovered plotted against atomic numberYear Discovered for 108 of the 118 elements, from 1250 to 2010 . When each element was first isolated or identified. Elements known since antiquity are excluded from the plot.123456712501440163018202010 Hydrogen (H): 1766 Helium (He): 1868 Lithium (Li): 1817 Beryllium (Be): 1798 Boron (B): 1808 Nitrogen (N): 1772 Oxygen (O): 1774 Fluorine (F): 1886 Neon (Ne): 1898 Sodium (Na): 1807 Magnesium (Mg): 1755 Aluminium (Al): 1825 Silicon (Si): 1824 Phosphorus (P): 1669 Chlorine (Cl): 1774 Argon (Ar): 1894 Potassium (K): 1807 Calcium (Ca): 1808 Scandium (Sc): 1879 Titanium (Ti): 1791 Vanadium (V): 1801 Chromium (Cr): 1797 Manganese (Mn): 1774 Cobalt (Co): 1735 Nickel (Ni): 1751 Zinc (Zn): 1746 Gallium (Ga): 1875 Germanium (Ge): 1886 Arsenic (As): 1250 Selenium (Se): 1817 Bromine (Br): 1826 Krypton (Kr): 1898 Rubidium (Rb): 1861 Strontium (Sr): 1790 Yttrium (Y): 1794 Zirconium (Zr): 1789 Niobium (Nb): 1801 Molybdenum (Mo): 1781 Technetium (Tc): 1937 Ruthenium (Ru): 1844 Rhodium (Rh): 1803 Palladium (Pd): 1803 Cadmium (Cd): 1817 Indium (In): 1863 Tellurium (Te): 1782 Iodine (I): 1811 Xenon (Xe): 1898 Cesium (Cs): 1860 Barium (Ba): 1808 Lanthanum (La): 1839 Cerium (Ce): 1803 Praseodymium (Pr): 1885 Neodymium (Nd): 1885 Promethium (Pm): 1945 Samarium (Sm): 1879 Europium (Eu): 1901 Gadolinium (Gd): 1880 Terbium (Tb): 1843 Dysprosium (Dy): 1886 Holmium (Ho): 1878 Erbium (Er): 1843 Thulium (Tm): 1879 Ytterbium (Yb): 1878 Lutetium (Lu): 1907 Hafnium (Hf): 1923 Tantalum (Ta): 1802 Tungsten (W): 1783 Rhenium (Re): 1925 Osmium (Os): 1803 Iridium (Ir): 1803 Platinum (Pt): 1735 Thallium (Tl): 1861 Bismuth (Bi): 1753 Polonium (Po): 1898 Astatine (At): 1940 Radon (Rn): 1900 Francium (Fr): 1939 Radium (Ra): 1898 Actinium (Ac): 1899 Thorium (Th): 1829 Protactinium (Pa): 1913 Uranium (U): 1789 Neptunium (Np): 1940 Plutonium (Pu): 1940 Americium (Am): 1944 Curium (Cm): 1944 Berkelium (Bk): 1949 Californium (Cf): 1950 Einsteinium (Es): 1952 Fermium (Fm): 1952 Mendelevium (Md): 1955 Nobelium (No): 1966 Lawrencium (Lr): 1961 Rutherfordium (Rf): 1964 Dubnium (Db): 1967 Seaborgium (Sg): 1974 Bohrium (Bh): 1981 Hassium (Hs): 1984 Meitnerium (Mt): 1982 Darmstadtium (Ds): 1994 Roentgenium (Rg): 1994 Copernicium (Cn): 1996 Nihonium (Nh): 2003 Flerovium (Fl): 1998 Moscovium (Mc): 2003 Livermorium (Lv): 2000 Tennessine (Ts): 2010 Oganesson (Og): 2002 Period
108 of 118 elements have a measured value.1250 – 2010

10 elements have no measured value for this property, so they are left out of the plot rather than drawn as zero. Almost all of them are synthetic elements that have never existed in weighable quantities.

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