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The British chemist John Dalton believed that every element is made of atoms that are all similar. He also believed that different elements have atoms of various masses. He imagined atoms as tiny solid spheres.
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British scientist J.J. Thomson discovered the electron. He eventually presented a new model, saying that an atom is a positively charged ball with electrons embedded in it.
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Japanese physicist Hantaro Nakaoka presented a new model of the atom that had a large ball in the center with a positive charge. The model showed the electrons spinning around the ball like the planets around the sun.
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British physicist Ernest Rutherford decided that the atom is mostly empty space. Electrons spin randomply around a small, positively charged nucleus.
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Danish physicist Niels Bohr created a model that showed electrons moving in specific shells rather than randomly. He said
that atoms take in or give off energy from one shell to the other. -
British physicist James Chadwick discovered the neutron. The existence of neutrons explained why atoms were heavier than the entire mass of their protons and electrons.
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Th current atomic model results from work done from the 1920's to the present. Electrons form a negatively charged clound around the nucleus. It isnt possible to figure out exactly where an electron is at any given time,.
