La cuarta revolución química (1945-1966). De las sustancias a las especies químicas

With educational purposes, a new chronology is introduced to address the history of chemistry around five revolutionary moments, analysing in this article only the fourth of them. Each revolution is considered in terms of the Kuhnian notion of 'exemplar' rather than 'paradigm'. This approach enables the incorporation into the revolutionary process of the instruments that contributed to their establishment, as well as the concepts that were developed and the derived subdisciplines. It is recognized, beyond a dogma, the way in which several 'hidden entities' very important in the teaching of chemistry -such as atoms, molecules, electrons or, in this case, spin- are consolidated. It also traces the passage of the substances to the chemical species.