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Dalton recognized that atoms of an element are different from other elements. He theorized that atoms are indivisable.
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In 1897 he discovered electrons, which he called corpuscles. He recognized electrons as components of atoms, but he did not yet know of the nucleus.
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He realized that the positive charge was localized in the nucleus of the atom but he could not explain why the electrons orbited around the nucleus.
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He proposed stable electron orbits and explained the emission spectra of some elements. He thought that the moving electrons should emit energy and crash into the nucleus but the model did not work for heavy elements.
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He discovered that electrons do not move in set paths but in waves. This is the most accurate and accepted model of the atom.
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