Plum pudding model: Difference between revisions

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Despite Thomson's efforts, his model couldn't account for [[emission spectra]] and [[Valence (chemistry)|valencies]]. Based on experimental studies of alpha particle scattering (in [[Rutherford scattering experiments|the gold foil experiment]]), [[Ernest Rutherford]] developed an alternative [[Rutherford model|model for the atom]] featuring a compact nucleus where the positive charge is concentrated.

Thomson's model is popularly referred to as the "plum pudding model" with the notion that the electrons are distributed uniformly like raisins in a tasty [[plum pudding]]. Neither Thomson nor his colleagues ever used this analogy.<ref name="HonGoldstein2013">{{Cite journal |author1=Giora Hon |author2=Bernard R. Goldstein |date=6 September 2013 |title=J. J. Thomson's plum-pudding atomic model: The making of a scientific myth |url=https://onlinelibrary.wiley.com/doi/10.1002/andp.201300732 |journal=Annalen der Physik |volume=525 |issue=8–9 |pages=A129–A133 |bibcode=2013AnP...525A.129H |doi=10.1002/andp.201300732}}</ref> It seems to have been coined by popular science writers to make the model easier to understand for the layman. The analogy is perhaps misleading because Thomson likened the positive sphere to a liquid rather than a solid since he thought the electrons moved around in it.<ref>Letter from J. J. Thomson to Oliver Lodge dated 11 April 1904, quoted in {{harvnb|Davis|Falconer|1997|p=153}}:<br />

"With regard to positive electrification I have been in the habit of using the crude analogy of a liquid with a certain amount of cohesion, enough to keep it from flying to bits under its own repulsion. I have however always tried to keep the physical conception of the positive electricity in the background because I have always had hopes (not yet realised) of being able to do without positive electrification as a separate entity and to replace it by some property of the corpuscles."<br /></ref>