<Tr> <Td> Electron e − </Td> <Td> elementary (lepton) </Td> <Td> G. Johnstone Stoney (1874) </Td> <Td> J.J. Thomson (1897) </Td> <Td> Minimum unit of electrical charge, for which Stoney suggested the name in 1891 . </Td> </Tr> <Tr> <Td> alpha particle α </Td> <Td> composite (atomic nucleus) </Td> <Td> never </Td> <Td> Ernest Rutherford (1899) </Td> <Td> Proven by Rutherford and Thomas Royds in 1907 to be helium nuclei . </Td> </Tr> <Tr> <Td> Photon γ </Td> <Td> elementary (quantum) </Td> <Td> Max Planck (1900) </Td> <Td> Albert Einstein (1905) or Ernest Rutherford (1899) as γ rays </Td> <Td> Necessary to solve the problem of black body radiation in thermodynamics . </Td> </Tr> <Tr> <Td> Proton p </Td> <Td> composite (baryon) </Td> <Td> Long ago </Td> <Td> Ernest Rutherford (1919, named 1920) </Td> <Td> The nucleus of 1 . </Td> </Tr>

Who proved the presence of neutral subatomic particles