The Saga of Atomic Weights

The atomic weight of elements is one single idea that distinguishes Dalton’s atomic theory from earlier atomistic ideas about the nature of matter. The concept of atomic weight also makes possible all the quantitative predictions about chemical interactions, and their outcomes. We take the idea of atomic weight as given, and almost never think of it as a conceptual framework which is the result of intense debates beginning in the early nineteenth century. The saga of atomic weights is not only extremely interesting, but it also gives us an understanding of the way scientists work. This story takes a winding route and is enriched by the contributions of several leading scientists of the time. Some of the debate around this concept continues even today.