By studying with Rutherford the transmutation of radioactive elements, Frederick Soddy set out the theory of isotopes in 1913. In the previous year J.J. Thomson seconded by Aston had separated two beams of neon atoms by deflection in an electro-magnetic field.
After the war, Aston can finally continue his work. He correctly assumes that the two populations of neon atoms are isotopes. More accurate measurements are needed to go further. Aston improves the mass spectrograph in 1919 by focusing the electromagnetic beam. He starts a systematic study of the chemical elements and discovers more than 200 non-radioactive isotopes.
Considering that a Nobel jury appreciates the experimentation, the award to Aston after only 3 years of personal work is highly deserved. His measurements with an unprecedented accuracy in that field led to assess the relative mass of the atoms on a scale centered on the value 16 for oxygen and to know the proportion of natural isotopes for all elements.
The results of Aston are irrefutable and conclusive. In 1920, he demonstrates the whole number rule. The arithmetic falls every time to an integer, solving one of the mysteries of chemistry: the atomic weight of an element is not an integer because it results from a mixing of isotopes, each of them matching a whole number.
Aston still manages to improve the accuracy of his measurements and discovers small variations around 1% from the integers. With a remarkable insight, he assumes the existence of forces ensuring the stability of the nucleus and the duality between energy and matter. This achievement opens the way for the nuclear physics.
In 1932, Chadwick discovers the neutron, an electrically neutral particle slightly heavier than the proton, fully explaining the deviations observed by Aston.
A large lot of memories around Aston's scientific work including his Nobel medal and diploma is estimated £ 200K for sale by Bonhams in London on June 15, lot 112. Please watch the video shared by the auction house.
A similarly constituted lot including the Nobel medal and diploma awarded to Chadwick in physics in 1935 was sold for $ 330K including premium by Sotheby's on June 3, 2014.