Chlorine played a prominent role in the discovery of isotopes. The famous Cavendish Laboratory scientists were fascinated with the atomic mass of Cl. Most elements have a mass that is a close approximation of the multiple of hydrogen (e.g., Aston 1927). By 1920, it was recognized that the atomic weight of Cl was ~35.5, which appeared to violate Francis Aston’s whole number rule. Sir Joseph J. Thomson started the famous “Discussion on Isotopes” (Thomson et al. 1921) with the following: “I will plunge at once into the most dramatic case of the isotopes—the case of chlorine”. The...

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.