What is the whole-number rule in chemistry?
The whole-number rule states that the atomic weights of isotopes are very nearly whole numbers, when expressed on the scale where oxygen is 16. This emerged from my mass spectrograph measurements. For example, chlorine has two isotopes: one at mass 35 and another at 37, both close to integers. The rule holds with remarkable accuracy for light elements, though deviations occur due to the packing fraction—the small difference between an isotope's actual mass and the sum of its constituent protons and neutrons. This packing fraction reflects the binding energy within the nucleus. The evidence suggests that the whole-number rule is a fundamental consequence of nuclear structure, and it was crucial in confirming Prout's hypothesis that all atoms are built from hydrogen nuclei.
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