A. van den Broek

The Discovery of the Proton (A. van den Broek)

In 1913 A. van den Broek suggested that it was a mistake to compare the charge on the nucleus with the atomic weight of the element. He suggested that the charge should be compared with the atomic number, which specifies the position of the element in the periodic table. (Hydrogen has an atomic number of 1, helium is 2, and so on.) Within experimental error, the estimate of the charge on the nucleus obtained from a-particle scattering experiments is equal to the atomic number of the element.