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John Dalton
In 1803 John Dalton proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. -
Dalton's Model
Dalton's advances athomic theory was said that they had different atoms and also revealed that you can not divide an atom into smaller pieces. -
William Crooke
Crookes' discovered the electron. He did so by reconstructing the Cathode Ray. Crookes' put black vanes on one side and silver on the other, which cause the vacuum tube to spin when it hit light. -
J.J Thompson
In 1897 J.J Thompson used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. -
J.J Thomson Model Plum Pudding Atomic Model
Each atom was a sphere filled with a positively charged fluid. The fluid was called the "pudding" Scattered in this fluid were the electrons knows as the plums.The radius of the model was 10 meters. Thomson suggested that the positive fluid held negative charges, the electrons because of electrical forces. -
Ernest Rutherford
He demonstrated that the atom has an internal structure of a small, dense nucleus about which negatively charged electrons circle in orbits.The Gold Foil expermient involved the firing of radioactive particles through minutely thin metal foils and detecting them using screens coated with zinc sulfide. -
Rutherford Model
Rutherford conducted what is now a famous experiment where he bombarded gold foil with alpha particles (Helium nuclei). A source which undergoes alpha decay is placed in a lead box with a small hole in it. Any of the alpha particles which hit the inside of the box are simply stopped by the box. Only those which pass through the opening are allowed to escape, and they follow a straight line to the gold foil. -
Quantum Mechanical Model
The quantum mechanical model is based on quantum theory, which says matter also has properties associated with waves. According to quantum theory, it’s impossible to know the exact position and momentum of an electron at the same time. This is known as the Uncertainty Principle.
The quantum mechanical model of the atom uses complex shapes of orbitals (sometimes called electron clouds), volumes of space in which there is likely to be an electron. -
Niel Bohr
Niels Bohr developed an explanation of atomic structure that agrees with the periodic table of elements. -
The Bohr Model
In atomic physics, the Bohr model, devised by Niels Bohr, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus--similar in structure to the solar system, but with electrostatic forces providing attraction. -
James Chadwick
James Chadwick used alpah particles in an experiment and discovered a neutral atomic particle with a mass close to a proton, discovering the neutrons. -
Bibliography (Because some did not fit in the descriptions).
1) "The Rutherford Model." Oswego City School District Regents Exam Prep Center. N.p., n.d. Web. 4 Sept. 2013. http://www.regentsprep.org/regents/physics/phys05/catomodel/ruther.htm.
2) " John Dalton | Chemical Heritage Foundation." Homepage of the Chemical Heritage Foundation | Chemical Heritage Foundation. N.p., n.d. Web. 4 Sept. 2013. http://www.chemheritage.org/discover/online-resources/chemistry-in-history/themes/table/dalton.aspx. -
Bibliography Continued
3) "Atomic Structure Timeline." Atomic Structure Timeline. N.p., n.d. Web. 4 Sept. 2013. http://atomictimeline.net/index.php.
SparkNotes: The Quantum Mechanical Model of the Atom." SparkNotes: Today's Most Popular Study Guides. N.p., n.d. Web. 4 Sept. 2013. 4)http://www.sparknotes.com/testprep/books/sat2/chemistry/chapter4section4.rhtml.
5)"Sir William Crookes (British chemist) -- Encyclopedia Britannica." Encyclopedia Britannica. N.p., n.d. Web. 4 Sept. 2013. <http://www.britannica.
