Talk:Plum pudding model

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Reorient to beta particle scattering

@Johnjbarton: Now that Headbomb has agreed that the maths stuff for the Thomson model should be in the Rutherford scattering experiments, I think we should rework the stuff in this article to beta particle scattering. That should do better historical justice to Thomson's work, which is something you want. Kurzon (talk) 20:39, 26 September 2024 (UTC)[reply]

@Johnjbarton: On that note, could you direct me to some papers by Thomson which contain his beta scattering studies? You mentioned several times that the plum pudding model lined up with Thomson's data on beta scattering, I want to look at that. Kurzon (talk) 10:43, 27 September 2024 (UTC)[reply]

Image is upside down

In the section "Deflection by the positive sphere", the image Thomson_model_alpha_particle_scattering_3.svg show a deflection away from the center correct for + on + scattering. However the Thomson's model was for beta particles, - on + and thus the deflection should be towards the center. This difference does not alter the model's predictions because every path on one side of the atom has a matching one on the other and they are added to compare to experiment. Johnjbarton (talk) 17:38, 27 September 2024 (UTC)[reply]

Right, I will get on that. Kurzon (talk) 17:49, 27 September 2024 (UTC)[reply]

Positive units

@Johnjbarton" and Tjlafave: In his 1910 paper, Thomson presented an equation that modeled beta scattering in the scenario where the positive charge exists in discrete units.

${\bar {\theta }}_{2}={\frac {16}{5}}\cdot {\frac {kq_{e}q_{e}}{mv^{2}}}\cdot {\frac {1}{R}}\cdot {\sqrt {\frac {3N}{2}}}{\sqrt {1-\left(1-{\frac {\pi }{8}}\right){\sqrt {\sigma }}}}$

Heilbron doesn't offer a guess as to how Thomson came up with this equation. Thomson doesn't call these units particles and I assume they're just as permeable as the positive sphere. If the positive charge units were particles then a direct collision would affect an alpha particle much differently. Is it correct of me to say that Thomson came close to deducing the existence of the proton? Rutherford deduced the existence of protons based on charge numbers of atoms. Interactions between particles is not just a question of electric fields because neutrons can split nucleui.

It's strange that Thomson did not propose the existence of the proton in his atomic model. Wasn't there enough information at the time to suggest the existence of protons if not prove them? Physicists at the time speculated on the existence of "positive electrons" that carried the elementary unit of positive charge just as negative electrons carry the elementary negative charge. Hydrogen ions and alpha particles were positively-charged particles. Thomson did not know exactly how many electrons were in an atom so perhaps a hydrogen ion could contain some remaining electrons. I suppose the missing piece of the puzzle was the nucleus, where the positive charge existed separate from the negative charge and therefore could be probed separately. Kurzon (talk) 20:41, 12 October 2024 (UTC)[reply]

Kepler?

@Johnjbarton:

$\theta =2\arctan {\frac {kq_{1}q_{2}}{mv^{2}b}}$

Did Kepler come up with this equation? In the Rutherford scattering article, you mentioned Kepler in the part where we explain how Rutherford calculated the scattering angle.Kurzon (talk) 20:41, 16 March 2025 (UTC)[reply]