Year: 2008 Pages: 13
- Atoms don't comprise nuclei and electron shells.
- Nuclei don't comprise Z protons and (A ? Z) neutrons.
- There are no perpetually spinning protons, neutrons and electrons.
Rutherford's scattering experiments and Moseley's X-ray experiments are not crucial for the nuclear atomic model. The same set of data can be explained by another atomic model.
The main characteristics of the Rutherford-Bohr-Chadwick nuclear atomic model are:
- A nucleus, which is made up of Z protons and (A ? Z) neutrons, where A is mass number and Z is the atomic number of the periodic table
- An electron cloud is located around the nucleus.
The Z extra nuclear electrons are placed in shells. The electron shells are arranged according to aufbau rules that determine spins and angular momenta of the electrons. Similar rules exist for the arrangement of nuclear shells. Both, scattering experiments with metal foils and X-ray experiments for nearly all elements were able to introduce the atomic number Z of target atoms as the variable of the corresponding metal foils or of the corresponding elements, respectively. This supposition is not justified because
- Rutherford's scattering theory considers electrostatic scattering only and disregards therefore the magnetic scattering effect.
- Most elements possess isotopes, which have obviously the same atomic number Z.
Rutherford left out of consideration isotope scattering experiments. According to Rutherford, the scattering of Sn-112 and Sn-124 (for example) is identical, but this is improbable, rather an isotope shift can be expected. Presumably, the isotope shift is due to magnetic scattering too. Consequently, it is not possible to infer that the distinctive property for scattering is atomic number Z.
Rutherford's scattering formula allows not in the least to infer that the atom consists of a nucleus with Z protons, (A-Z) neutrons and Z extra nuclear electrons. Mass number A is probably the predominant distinctive property for scattering. But there are isobars (same A) that should yield different scattering results. Then allotropes are known, for instance two for K-40, which have different atomic structures and therefore should have different scattering features.