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Scientists who discovered atoms
science and atoms stuff
Terms in this set (4)
(early nineteenth century) He combined an idea of elements with the earlier theory of atoms. He had the following ideas about matter: (1) matter is made up of atoms. (2) Atoms cannot be divided into smaller pieces. (3) All the atoms of an element are exactly alike. (4) different elements are made of different kinds of atoms. He pictured an atom as a hard shere that was the same throughout.
(second half of nineteenth century) He tested Daltons theory. He did an experiment wit a glass tube that had no air in it and two pieces of metal called electrodes sealed inside. The electrodes were connected to a battery by wires. With this experiment it was discovered by Thomsom that there are smaller particles then an atom (. The cathode ray was used for t.v. and computer monitors for many years.
J. J. Thomson
(1897) He tested to see if the light in crookes cathode ray was light or particles he put a magnet by the cathode ray and the light had bent so that ment that it was particles. Then he tested to see if it would be the same if there were different gasses and metals used in it. That way he learned that the cathode ray was negatively charged particles. So, he had discovered negatively charged particles called eletrons! He pictured the atom as a ball that contains negatively charged particles speard evenly throughout the atom and the "clay" part was positive.
(1906) He's crew and him did an experiment were they would fire alpha particles (fast moving positively charged particles) at a thin film of gold. In the experiment he expected the alpha particles to go through the film because the film didn't have enough matter, but instead the particles were veering of in large angles and some bounced back. Only a very large positive charge would be able to cause the alpha particles to bounce back. Thomsons model of the atoms was distributed evenly and could not have repelled an alpha particle. He discovered protons. He knew there was space in the atom. He thought that almost all of an atoms mass & all of its positive charges were cramped into an incredibly small region of space.