1877-1945

British chemist and physicist who was awarded the 1922 Nobel Prize for Chemistry for discoveries and research in mass spectrography. Aston invented the mass spectrograph in 1919. His spectrographic observations led him to put forward the whole-number, or Aston rule, according to which atomic weights are always whole numbers. He correctly attributed apparent deviations from this rule to the presence of isotopes. His later measurements of isotopic masses allowed more accurate estimates of nuclear binding energies.