<Table> <Tr> <Th> Time </Th> <Th> Event </Th> </Tr> <Tr> <Td> 1800 </Td> <Td> William Herschel discovers `` heat rays '' </Td> </Tr> <Tr> <Td> 1801 </Td> <Td> Johann Wilhelm Ritter made the hallmark observation that invisible rays just beyond the violet end of the visible spectrum were especially effective at lightening silver chloride - soaked paper . He called them `` oxidizing rays '' to emphasize chemical reactivity and to distinguish them from `` heat rays '' at the other end of the invisible spectrum ( both of which were later determined to be photons ) . The more general term `` chemical rays '' was adopted shortly thereafter to describe the oxidizing rays , and it remained popular throughout the 19th century . The terms chemical and heat rays were eventually dropped in favor of ultraviolet and infrared radiation , respectively . </Td> </Tr> <Tr> <Td> 1895 </Td> <Td> Discovery of the ultraviolet radiation below 200 nm , named vacuum ultraviolet ( later identified as photons ) because it is strongly absorbed by air , by the German physicist Victor Schumann </Td> </Tr> <Tr> <Td> 1895 </Td> <Td> X-ray produced by Wilhelm Röntgen ( later identified as photons ) </Td> </Tr> <Tr> <Td> 1897 </Td> <Td> Electron discovered by J.J. Thomson </Td> </Tr> <Tr> <Td> 1899 </Td> <Td> Alpha particle discovered by Ernest Rutherford in uranium radiation </Td> </Tr> <Tr> <Td> 1900 </Td> <Td> Gamma ray ( a high - energy photon ) discovered by Paul Villard in uranium decay </Td> </Tr> <Tr> <Td> 1911 </Td> <Td> Atomic nucleus identified by Ernest Rutherford , based on scattering observed by Hans Geiger and Ernest Marsden </Td> </Tr> <Tr> <Td> 1919 </Td> <Td> Proton discovered by Ernest Rutherford </Td> </Tr> <Tr> <Td> 1931 </Td> <Td> Deuteron discovered by Harold Urey ( predicted by Rutherford in 1920 ) </Td> </Tr> <Tr> <Td> 1932 </Td> <Td> Neutron discovered by James Chadwick ( predicted by Rutherford in 1920 ) Main article : Discovery of the neutron </Td> </Tr> <Tr> <Td> 1932 </Td> <Td> Antielectron ( or positron ) , the first antiparticle , discovered by Carl D. Anderson ( proposed by Paul Dirac in 1927 and by Ettore Majorana in 1928 ) </Td> </Tr> <Tr> <Td> 1937 </Td> <Td> Muon ( or mu lepton ) discovered by Seth Neddermeyer , Carl D. Anderson , J.C. Street , and E.C. Stevenson , using cloud chamber measurements of cosmic rays ( it was mistaken for the pion until 1947 ) </Td> </Tr> <Tr> <Td> 1947 </Td> <Td> Pion ( or pi meson ) discovered by C.F. Powell 's group , including César Lattes ( first author ) and Giuseppe Occhialini ( predicted by Hideki Yukawa in 1935 ) </Td> </Tr> <Tr> <Td> 1947 </Td> <Td> Kaon ( or K meson ) , the first strange particle , discovered by George Dixon Rochester and Clifford Charles Butler </Td> </Tr> <Tr> <Td> 1950 </Td> <Td> Λ ( or lamda baryon ) discovered during a study of cosmic - ray interactions </Td> </Tr> <Tr> <Td> 1955 </Td> <Td> Antiproton discovered by Owen Chamberlain , Emilio Segrè , Clyde Wiegand , and Thomas Ypsilantis </Td> </Tr> <Tr> <Td> 1956 </Td> <Td> Electron antineutrino detected by Frederick Reines and Clyde Cowan ( proposed by Wolfgang Pauli in 1930 to explain the apparent violation of conservation of energy in beta decay ) At the time it was simply referred to as neutrino since there was only one known neutrino . </Td> </Tr> <Tr> <Td> 1962 </Td> <Td> Muon neutrino ( or mu neutrino ) shown to be distinct from the electron neutrino by a group headed by Leon Lederman </Td> </Tr> <Tr> <Td> 1964 </Td> <Td> Xi baryon discovery at Brookhaven National Laboratory </Td> </Tr> <Tr> <Td> 1969 </Td> <Td> Partons ( internal constituents of hadrons ) observed in deep inelastic scattering experiments between protons and electrons at SLAC ; this was eventually associated with the quark model ( predicted by Murray Gell - Mann and George Zweig in 1964 ) and thus constitutes the discovery of the up quark , down quark , and strange quark . </Td> </Tr> <Tr> <Td> </Td> <Td> J / ψ meson discovered by groups headed by Burton Richter and Samuel Ting , demonstrating the existence of the charm quark ( proposed by James Bjorken and Sheldon Lee Glashow in 1964 ) </Td> </Tr> <Tr> <Td> </Td> <Td> Tau discovered by a group headed by Martin Perl </Td> </Tr> <Tr> <Td> 1977 </Td> <Td> Upsilon meson discovered at Fermilab , demonstrating the existence of the bottom quark ( proposed by Kobayashi and Maskawa in 1973 ) </Td> </Tr> <Tr> <Td> 1979 </Td> <Td> Gluon observed indirectly in three - jet events at DESY </Td> </Tr> <Tr> <Td> </Td> <Td> W and Z bosons discovered by
who discovered the subatomic particles of an atom
J.J. Thomson Ernest Rutherford James Chadwick