CH301 - chapter 5 notes

CH301 - chapter 5 notes - 1 General Chemistry I Chapter 5 A...

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1 General Chemistry I Chapter 5 A good portion of the beginning of this chapter deals with the history of the discovery of the fundamental particles. We will not cover this particular material during class lecture, however, you will be held responsible for reading the material and knowing the names of a few the scientists and the results of their respective experiments. (Several figures describe the various experiments conducted to understand the fundamental particles of the atom. As you read, pay close attention to the material in these figures . The information outlined below and the homework questions will guide you in determining which material you should read carefully. 5-1 Fundamental Particles 5-2 The Discovery of Electrons 1. The work of J. J. Thompson (Figure 5-1) cathode-ray tube experiment the particles of the cathode rays have mass the particles of the cathode rays have a negative charge named the negatively charged particle electron determined the charge to mass ratio of the electron 2. The work of Robert Millikan (Figure 5-2) oil-drop experiment determined the magnitude of the charge of the electron 5-3 Canal Rays and Protons (Figure 5-3) 1. The work of Eugene Goldstein cathode-ray tube experiment canal rays particles of the canal rays have a positive charge that is equal in magnitude to the electron positive charges called protons 5-4 Rutherford and The Nuclear Atom (Figure 5-5) 1. The work of Ernest Rutherford alpha ( α ) particles gold foil experiment atomic nucleus of each atom contains a tiny, positively charged, massive center Particle Mass (amu ) Charge Electron (e - ) 0.00054858 -1 Proton (p,p + ) 1.0073 +1 Neutron(n,n 0 ) 1.0087 0
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2 5-5 Î 5-7 and 5-9 Atomic Number (Z), Neutrons, Mass Number (A), Isotopes and Atomic Weight 1. Atomic number: The atomic number is the number of protons in all the atoms of a particular element. The atomic number is constant and does not change in the atoms of a particular element. The symbol for the atomic number is Z. 2. Neutrons: The number of neutrons may differ for atoms of the same element (Chadwick’s work). Atoms of the same element that have different numbers of neutrons are called isotopes . The mass of a neutron is slightly larger than that of a proton (n o = p + + e ) 3. Mass Number: The mass number of an atom of a particular element is equal to the number of protons + the number of neutrons. The mass number of all the atoms of a particular element is equal to the average mass of the percentages of the different isotopes. The mass number is expressed in atomic mass units for the mass of single atoms and the average atomic mass. Atomic mass and atomic weight are the same. Mass number is given the symbol A.
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CH301 - chapter 5 notes - 1 General Chemistry I Chapter 5 A...

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