He first proposed the existance of an ultimate particle.
John Dalton (1766-1844).
Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.
Proposed the perodic law asnd developed the first periodic table
John (J. J.) Thomson
Studied "canal rays" and found they were associated with the proton H+ .
Determined the unit of charge of the electron
publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons.
Discovered Moseley's law is an empirical law concerning the characteristic x-rays that are emitted by atoms.
He is best known for his uncertainty principle, which restricts the accuracy with which some properties of atoms and particles--such as position and linear momentum--can be determined simultaneously
discovered a third type of subatomic particle, which he named the neutron.
Edwin Schrodinger stated that rather than electrons being distributed within an electron configuration of shells and energy levels, they were arranged in orbitals which were systematically distributed within Electron Clouds.