<Tr> <Th> </Th> <Th> </Th> <Th> 1789 </Th> <Th_colspan="1"> A. Lavoisier </Th> <Th> </Th> <Th> </Th> <Th> The first modern list of chemical elements--containing 33 elements including light, heat, unextracted "radicals" and some oxides . He also redefined the term "element". Until then, no metals except mercury were considered elements . </Th> </Tr> <Tr> <Td> 40 </Td> <Td> Zirconium </Td> <Td> 1789 </Td> <Td> H. Klaproth </Td> <Td> 1824 </Td> <Td> J. Berzelius </Td> <Td> Klaproth identified a new element in zirconia . </Td> </Tr> <Tr> <Td> 92 </Td> <Td> Uranium </Td> <Td> 1789 </Td> <Td> H. Klaproth </Td> <Td> 1841 </Td> <Td> E. - M. Péligot </Td> <Td> Klaproth mistakenly identified a uranium oxide obtained from pitchblende as the element itself and named it after the recently discovered planet Uranus . </Td> </Tr> <Tr> <Td> 22 </Td> <Td> Titanium </Td> <Td> 1791 </Td> <Td> W. Gregor </Td> <Td> 1825 </Td> <Td> J. Berzelius </Td> <Td> Gregor found an oxide of a new metal in ilmenite; Martin Heinrich Klaproth independently discovered the element in rutile in 1795 and named it . The pure metallic form was only obtained in 1910 by Matthew A. Hunter . </Td> </Tr>

Who discovered that each element has a unique atomic number