During that time, scientists knew that there was a positive charge in the atom that balanced out the negative charges of the electrons, making the atom neutral, but they didn't know where the positive charge was coming from. Thomson in 1904, after the electron had been discovered, but before the atomic nuclei was discovered. The plum pudding model is an early 20th century model of an atom. You can help Wikipedia by reading Wikipedia:How to write Simple English pages, then simplifying the article. Still, Thomson's model (along with a similar Saturnian ring model for atomic electrons, put forward also in 1904 by Nagaoka after the Maxwell model of Saturn's rings), were earlier harbingers of the later and more successful solar-system-like Bohr model of the atom.The English used in this article or section may not be easy for everybody to understand. Thomson attempted to make his model account for some of the major spectral lines known for some elements, but was not notably successful at this. In Thomson's model, electrons were free to rotate in rings which were further stabilized by interactions between the electrons, and spectra were to be accounted for by energy differences of different ring orbits. These orbits were stabilized in the model by the fact that when an electron moved farther from the center of the positive cloud, it felt a larger net positive inward force, because there was more material of opposite charge, inside its orbit (A particle like a small black hole would feel the same restorative force if it penetrated the body of the Earth such a particle would feel only the gravity of the Earth inside its radius). The electrons were free to rotate within the blob or cloud of positive substance. Ī little-known (or now forgotten) fact about the original Thomson "plum pudding" model is that it was dynamic, not static. It has also been called the ' chocolate chip cookie model or "Blueberry Muffin Model"', but only by those who have not read Thomson's original paper ( On the Structure of the Atom: an Investigation of the Stability and Periods of Oscillation of a number of Corpuscles arranged at equal intervals around the Circumference of a Circle with Application of the Results to the Theory of Atomic Structure), published in the Philosophical Magazine (the leading British science journal of the day). Thomson's model was compared (though not by Thomson) to a British treat called plum pudding, hence the name. Eventually, by 1913, this work had culminated in the solar-system-like (but quantum-limited) Bohr model of the atom, in which a nucleus containing an atomic number of positive charge is surrounded by an equal number of electrons in orbital shells. The model was disproved by the 1909 gold foil experiment, which was interpreted by Ernest Rutherford in 1911 to imply a very small nucleus of the atom containing a very high positive charge (enough to balance about 100 electrons in gold), thus leading to the Rutherford model of the atom, and finally (after Henry Moseley's work showed in 1913 that the nuclear charge was very close to the atomic number) to the Antonius Van den Broek suggestion that atomic number is nuclear charge. Recognize and detect the effects of electrostatic charges on your balance
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