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The Solid Sphere Model was the first atomic model and was developed by John Dalton in the early 19th century. He hypothesized that an atom is a solid sphere that could not be divided into smaller particles. He came up with his theory as a result of his research into gases. He realized that certain gases only combined in specific proportions.
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The plum pudding model (also known as Thomson’s plum pudding model) is a historical scientific models of the atom. The plum pudding model is defined by electrons surrounded by a volume of positive charge, like negatively-charged “plums” embedded in a positively-charged “pudding” (hence the name).