chem chap 2 - • In chemical reactions, atoms are...

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Foundations of the Atomic Theory • Law of Conservation of Mass—mass is neither created nor destroyed during ordinary chemical reactions • Law of Definite Proportions—a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound • Law of Multiple Proportions—if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with the mass of the first element is always the ratio of small whole #’s o Masses increase proportionally to the number of atoms Dalton’s Atomic Theory • All matter is composed of extremely small particles called atoms • Atoms of a given element are identical in size, mass an other properties • Atoms cannot be created, subdivided, or destroyed • Atoms of different elements combine in simple whole #’s ratios to form chemical reactions
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Unformatted text preview: • In chemical reactions, atoms are combined, separated and rearranged Structure of the Atom • Protons—positively charge • Neutrons—neutral charge • Electrons—negatively charge Discovery of the Atomic Nucleus • Ernest Rutherford o Gold Foil Experiment Discovery of the nucleus • EMPTY SPACE • Small, dense + charged • Alpha particles—positive charge particles with 4x the mass of a hydrogen atom • # of protons in an atom’s nucleus identify it Electron • J.J Thompson o Cathode ray tube experiment Filled it with gas under low pressure • Better conductor for electricity Shows that particles have mass • All elements have this negatively charged particle • Robert Milikan o Oil Drop Experiment Determined the exact charge and mass of the electron • Charge > Mass...
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This note was uploaded on 02/25/2012 for the course CHEM 2142 taught by Professor Roberts during the Fall '10 term at Texas State.

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