1. Democritus Law of Definite ______ Law of ______ Atomic Theory All matter is comprised of atoms Atoms are indivisible Cathode Ray Tube Exp. model These can be lost or gained e - /m ratio Charge on the electron ________ Oil-Drop Exp. Gold Foil Exp. Atom is mostly… Nucleons Most are… The Atom John Dalton Compostion Conservation Atoms of different elements have different masses Atoms rearrange in chem rxtions LaviosierProust J. J. Thomson The electron (negatively charged matter) 1.76x10 8 C/g Millikan’s Plum Pudding 1.6x10 -19 C mass of e - 9.11x10 -28 g ions Ernest Rutherford Nucleus (positive, dense core) empty protonsneutrons (+ charge) (no charge) Chadwick A Z Atomic #Mass # nuclide AXAX z Element-A A group of isotopes Atomic masses Weighted Averages Mass Spec. radioactive Alpha Beta Gamma matter (Energy) Equations to describe these Ionizing radiation Hard Little Spheres Planetary Model Chapter 3... HChem. History counting them The MOLE 1 mole = 6.02 x 10 23 = molar mass Use D.A. A particular atom

2. 3 H → 3 He + ___ The decay of hydrogen-3 1 2 0e-0e- (beta) 227 Th → 4  + ____ The alpha decay of thorium-227 90 2 223 Ra 88

3. When a sample of bromine atoms is injected into a mass spectrometer, the results obtained can be shown. Mass Number # of atoms (out of 10000) 79 81 50694931 Use the data to compute the atomic mass of natural bromine. (The mass values for 79 Br and 81 Br are 78.92 amu and 80.92 amu respectively.) (0.5069)(78.92 amu ) + (0.4931)(80.92 amu ) = 79.91 amu (50.69%)(49.31%)

4. Silver has two naturally occurring nuclides. One is silver-107 and the other silver-109. Knowing the atomic mass of silver is 107.9 amu, determine the relative abundance of each nuclide in a natural sample of silver if each nuclide has a relative atomic mass as given below: silver-107 = 106.905 amu silver-109 = 108.970 amu X(106.905 amu) + (1-X)(108.970 amu) = 107.9 amu 106.905X amu + (108.970 amu - 108.970Xamu) = 107.9 amu 106.905X amu - 108.970X amu = 107.9 amu - 108.970 amu -2.065X amu = -1.07 amuX = 0.518 Ag-107 = 51.8% Ag-109 = 48.2%

5. A sample of silver has a mass of 4.97 grams. How many silver atoms are in the sample? Also, how many of those atoms have 60 neutrons? 4.97 g Ag 6.02 x 10 23 atoms Ag Remember that silver-107 is 51.8% of the silver atoms in a sample of silver. 1 107.9 g Ag = 2.77 x 10 22 atoms Ag (0.518)(2.77 x 10 22 atoms silver) = 1.43 x 10 22 atoms of 107 Ag The test has: 20 multiple choice 16 fill in the blank 2 problem solving 1 essay!!!!!