Group1

Group 1: Keegan, Zack, Anna, Connor

**__Bohrs Model of the Atom__**

>> Neils Bohr used the theory of atomic spectra to bind al his referances together to create The Bohr Model of the Atom. Google Images." //Google//. N.p., n.d. Web. 18 Sept. 2011. .// //"Google Images." Google. N.p., n.d. Web. 19 Sept. 2011. .// **__ J.J. Thomson __** J.J. Thomson and his student, Ernest Rutherford discovered the electron after many experiments involving “the nature of electric discharge in a high-vacuum cathode-ray tube'' The original cathode ray tube consisted of a glass tube which had wires in oppisite ends. most of the air was pumped out of the tube and an electric charge was passed through the wires. where the light from the wires reached the glass a fluorescent glow was produced. The scientists assumed that some kind of ray was lighting up the glass. In Thomson's first cathode ray tube experiment he found that applying a magnetic field across the tube caused the negatively charged ray to be bent away. This proved that the charge could not be separated from the rays. In his second experiment he created a nearly perfect vacuum and found that the cathode rays would bend in an electric field. From these two experiments, he concluded that "cathode rays are charges of negative electricity carried by particles of matter." From Thomson's third experiment, he wanted to determine the propreties of the particles. Using the cathode ray tube he varied the strength of the electrical current and deduced the charge to mass ratio from how much the particles were bent. He found that the charge to mass ratio was extemely large and hypothesized that the cathode rays were made of particles that came from within atoms. These experiments eventually led to Thomson's idea for the structure of an atom. Atoms do not have an electric charge; therefore they must also contain positively charged particles called protons to counteract the effect of the negatively charged electrons. The Thomson model accounts for the positive and negative charges, assuming that they are scattered throughout the atom. However, further experiments by Rutherford showed that the protons were concentrated in the center of the atom and the electrons surround the protons.
 * Neils Henrik David Bohr was a very famous Danish physicist in the early 19th century. His main studies to physics involved: proving and understanding atomic structure, quantum mechanics, and the aid and construction of the Manhattan Project. Dr. Bohr describes that and atom consists of a nucleus made of neutrons and protons and multiple electrons orbiting the nucleus. Dr. Bohr determined this from studying these reference’s: //On The Constitution of Atom’s and Molecules part 1,2, and 3, The Spectre of Helium and Hydrogen, Atomic structure,// and, //Albert Einstein’s Zum Quantensatz von sommerfeld und Epstein,// Which was a collections of Albert Einsteins papers and research. Dr. Bohr worked with Max Planck and Ernest Rutherford to put all these pieces together.
 * **REFERANCES**





References: //“Historical models of the atom.”web.18 sept. 2011. []// //“Thomsons atomic model.”web. 18 sept. 2011. []// //Phillipchuk, Kelly, Bob Kvamme, Camille Hounjet, Ted View, Penny Mohr, Donald Lacy, Heather A. Mace, Kirsten Mah, Igor Nowikow, Joanne Neal, and Lionel Sandner.// Saskatchewan science 9//. Columbus: Pearson, 2011. Print.// //" Joseph John Thomson | Chemical Heritage Foundation."// Homepage of the Chemical Heritage Foundation | Chemical Heritage Foundation//. N.p., n.d. Web. 18 Sept. 2011. [].// //"A Look Inside the Atom."// American Institute of Physics//. N.p., n.d. Web. 9 Oct. 2011. .// //Shuttleworth, Martyn. "J. J. Thomson's Cathode Ray Experiment."// The Scientific Method, Science, Research and Experiments//. N.p., n.d. Web. 9 Oct. 2011. .//

__Rutherford __

- The experiment was conducted in 1911 by Hans Geiger and Ernest Marsden at the suggestion of Ernest Rutherford and they performed an experiment to test J.J Thompson’s plum pudding model. What they did was fire alpha particles (helium nuclei containing two positive charges) at a thin piece of gold foil, and measured the deflection of the particles as they came out through the other side from that they could deduce the information about the structure of the foil. They expected all of the alpha particles to be deflected just a little bit as they passed through the plum pudding but they soon found out that the particles they shot at the foil were not deflected at all, and had passed through undisturbed (most of them that were undisturbed bounced back) Geiger and Marsden had thought the same thing would happen “that the positive and negative charges were spread evenly throughout the atom and only the weak electric forces would be exerted on the alpha particles that were passing through the thin foil at such a high energy” which had been based on an earlier experiment but what they found (to their surprise) was that although the majority of alpha particles did pass straight through the gold foil approximately 1 in 8000. It lead them to Rutherford’s theory that most of the atom was made up of mostly ‘empty space’. ** References: ** Webpages: [] [] ** Pictures from: ** Google Images. (n.d.). Google. Retrieved September 16, 2011, from [] The, 1. t. (n.d.). Rutherford model of the atom. Indiana University Northwest. Retrieved September 19, 2011, from [] Summary //Early 1800's - John Dalton preformed experiments that identified the smallest particals in matter as atoms. obviously there are particles smaller than atoms.//

//1897- J.J. Thomson performed experiments and dicovered the electron. His model of the atom consisted of negitivly charged electrons floating in positivly charged matter. his student, Ernest Rutherford proved this not to be true.//

//1911- Ernest Rutherford's experiments showed that the negitively charged electrons surrounded a positive center, similar to a solar system. Rutherfords model of the atom was problematic. By the theory of electricity and magnatism, oppisite charges attract each other. Therefore the electrons should gradually spiral towards the positivly charged center, but this does not happen.//

//1912- Niels Bohr developed rules that discribed the way atoms operate. The electrons exist in orbits. The orbits have different energy levels and an electron can jump from one orbit to another either giving off or absorbing energy.//

//The Bohr atom works for simple elements like hydrogyen, but not for more complex ones because of the different shapes of the orbits. In addition, his theory was too simple to explain why a strong magnetic field changed the expected color of light the atom gave off when an electron jumped between orbits.//

//Reference://

//1920s, the, and further experiments showed that. "History of atoms."// NoBeliefs.com (Freethinkers)//. N.p., n.d. Web. 10 Oct. 2011. .