Atomic Theory
In ancient Greek the word atom meant the smallest indivisible particle that could be conceived. The atom was thought of as indestructible; in fact, the Greek word for atom means "not divisible." Knowledge about the size and make up of the atom grew very slowly as scientific theory progressed. What we know/theorize about the atom now began with a core theory devised by Democrotus, a Greek philosopher who proposed that matter consisted of various types of tiny discrete particles and that the properties of matter weredetermined by the properties of these particles. This core theory was then modified and altered over years by Dalton, Thompson, Rutherford, Bhor, and Chadwick. The atoms original structure was simple, but as more and more research was done the atom became more complex and puzzling. Our first benefactor of atomic theory was John Dalton, a man later nick-named the "Father of atomic theory" for his contribution of many theories and laws to modern atomic theory. His theories answered many questions of skeptical scientists: elements combine with one another to form chemical compounds and the atom doesn't change, atoms link together in definite proportions, all atoms of any element are all the same, the law of multiple p
Electrons in a "ground state" are in their regular energy level and give off no energy; however, if an electron is in an "excited state" it sends energy in quantum packets (photons) and light is observes. With much experimentation Thompson theorized that although the atom was made up of small particles it was not the same indestructible model proposed by Dalton. Ernest Rutherford was a major contributor to the atomic model because he proved that although Dalton and Thompson were partially correct there was still a flaw in both of their models of the atom. To his astonishment particles were through, came back, and some also were deflected to the sides of the gold foil. In 1932, through mass spectronomy, he discovered a heavy neutral particle with the mass of a proton. Rutherford and his assistants put a piece of radioactive material in a lead box with a small hole in one side to direct the alpha particles towards the gold foil, which was surrounded by zinc sulfide screens. When scientists added the weight of the electrons and the weight of the protons and subtracted that from the overall weight of the atom there was a remainder. Chadwick discovered the last piece of information about the atom. Thompson stated that protons and electrons were evenly distributed throughout the atom. Bibliography Sources: Textbook: Chemistry: The Study Of Matter, Simon and Schuster, copyright 1992Internet Source: http://encarta. A man named Milikin determined the mass of an electron to be 0 amu and the relative charge to be negative 1. One of the next most recognized people involved in the progression of atomic theory was J. There are seven levels, which were derived from the seven colors he saw, each of which has a specific number of electrons that it has capacity for.
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