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History of Chemistry-Elaine Gross pd. 4
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Dalton's Atomic Theory
Cemistry HistorypictureJohn Dalton published his atomic threory that stated all matter is composed of atoms. It also said that atoms are very tiny and invisible. -
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Protons
Chemistry HistorypictureEugene Goldstein discovered positive particles by using a tube filled with hydrogen gas (this tube was similar to Thomson's tube...see 1897). The positive particle had a charge equal and opposite to the electron. It also had a mass of 1.66E-24 grams or one atomic mass unit. The positive particle was named the proton. -
X-Ray
PictureChemistry HistoryWilhelm Roentgen accidentally discovered x-rays while researching the glow produced by cathode rays. Roentgen performed his research on cathode rays within a dark room and during his research, he noticed that a bottle of barium platinocyanide was glowing on a shelf. He discovered that the rays that were causing the fluorescence could also pass through glass, cardboard and walls. -
J.J. Thomson-The Electron and Its Properties
PictureChemistry HistoryJ.J. Thomson placed the Crookes' tube within a magnetic field. He found that the cathode rays were negatively charged and that each charge had a mass ratio of 1.759E8 coulombs per gram. He concluded that all atoms have this negative charge (through more experiments) and he renamed the cathode rays electrons. His model of the atom showed a sphere of positively charged material with negative electrons stuck in it. Thomson received the 1906 Nobel Prize in physics. -
Ernest Rutherford-3 Types of Radioactivity
PictureHistory ChemistryErnest Rutherford sent a radioactive source through a magnetic field. Some of the radioactivity was deflected to the positive plate; some of it was deflected to the negative plate; and the rest went through the magnetic field without deflection. Thus, there were three types of radioactivity: alpha particles (+), beta particles (-) and gamma rays (neutral). By performing other experiments and using this information, Rutherford created an atomic model different from Thomson's. Rutherford believed -
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Manhattan Project
PictureChemistry HistoryAlbert Einstein and Enrico Fermi both warned the United States about Germany's extensive research on atomic fission reaction. Below the football field at the University of Chicago, the United States developed the very first working nuclear fission reactor. The Manhattan Project was in process. -
Niels Henrik David Bohr-Manhatten Project
PictureChemistry HistoryHe helped with the Manhatten Project. He also made many scientific contributions by understanding the structure of an atom.
