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How did Thomson’s discovery change the atomic model?

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Bohr model diagram of a hydrogen atom showing a green nucleus labeled H, a single electron orbit, and text with atomic mass 1.008 and electron configuration 1. — atom The Bohr model describes the structure of atoms, in this case hydrogen.

J.J. Thomson’s discovery of the electron in 1897 fundamentally transformed the atomic model by proving that the atom was not an indivisible, homogeneous particle, as had been believed for over 2,000 years.123

By identifying a negatively charged particle much smaller than the smallest known atom, Thomson demonstrated that atoms possess a complex internal structure. To account for this, he supported the Thomson atomic model—popularly known as the "plum-pudding" model—which proposed that atoms were uniform spheres of positively charged matter with electrons embedded throughout, like raisins in a pudding.24315

This model addressed the requirement for electrical neutrality while providing a stable structure where displaced electrons would naturally return to their original positions. Although this model was eventually replaced by the Rutherford atomic model in 1911, Thomson’s work was pivotal in establishing the field of atomic physics and identifying the first subatomic particle.25164