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john dalton
1Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks.
2 He also noted that the atoms of one element differ from the atoms of all other elements. -
j.j thomson
1Thomson discovered the electron and then went on to propose a model for the structure of the atom.
2His work also led to the invention of the mass spectrograph -
ernest ruthford
1 He discovered alpha and beta rays, set forth the laws of radioactive decay, and identified alpha particles as helium nuclei.
2 He found that the atom consists mostly of empty space, with its mass concentrated in a central positively charged nucleus. -
neills bohr
1 proposed a theory for the hydrogen atom, based on quantum theory that some physical quantities only take discrete values
2 Bohr's model explained why atoms only emit light of fixed wavelengths, and later incorporated the theories on light quanta.