CREATORAston, Francis W.
TITLEMass Spectra and Isotopes
DATE ACCESSED17 February 2017

This web-based document consists of the Nobel lecture in chemistry that Francis W. Aston delivered on December 12, 1922 explaining his invention of the mass spectrograph, his use of it to isolate 212 of the naturally occurring atomic isotopes, and his conclusions drawn from those findings. The lecture first gives an explanation of subatomic structure, as well as the evolution of mass spectrograph technology. Aston then describes experiments he did on different elements to isolate their natural isotopes. He next outlines his Whole Number Rule theory, and states that the deviation from it posed by the conversion of hydrogen into helium is due to a portion of mass being destroyed during the process. Aston saw the significance of that deviation using Einstein’s theory of relativity, which shows the tremendous amount of energy that would be created by the annihilation of mass. In that recognition, Aston provided the next step in the scientific discoveries that would lead to the invention of the atomic and hydrogen bombs. The lecture is at an advanced level, and assumes knowledge of both physics and chemistry. Written before the discovery of the neutron, the lecture depicts the particle as a proton and an electron paired together.

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