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PowerPoint Slides Shown Wednesday, Oct. 01 2008

PowerPoint Slides Shown Wednesday, Oct. 01 2008. CH142B. Definitions-I. Matter - The “stuff” of the universe: books, planets, trees, professors - anything that has mass and volume. Composition - The types and amounts of simpler

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PowerPoint Slides Shown Wednesday, Oct. 01 2008

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  1. PowerPoint Slides Shown Wednesday, Oct. 01 2008 CH142B

  2. Definitions-I Matter- The “stuff” of the universe: books, planets, trees, professors - anything that has mass and volume. Composition - The types and amounts of simpler substances that make up a sample of matter. Properties - The characteristics that give each substance a unique identity. Physical Properties - are those the substance shows by itself, without interacting with another substance ( color, melting point, boiling point,density, etc.) Chemical Properties - are those that the substance shows as it interacts with, or transforms into, other substances (flammability, corrosiveness, etc.)

  3. Definitions - Mass & Weight Mass - The quantity of matter an object contains kilogram - ( kg ) - the SI base unit of mass, is a platinum - iridium cylinder kept in Paris as a standard! Weight - depends upon an object’s mass and the strength of the gravitational field pulling on it.

  4. Definitions - II Energy - The capacity to do work! Potential Energy - The energy due to the position of the object.Or Energy from a chemical reaction. Kinetic Energy - The energy due to the motion of the object.

  5. STATES OF MATTER • SOLIDS - definite shape and definite volume. Particles vibrate about fixed positions; interactions are between near neighbors only. • LIQUIDS - No definite shape yet a definite volume. Particles slide over near neighbors; short, random straight-line motion. • GASES - No definite shape and no definite volume. Long, random straight-line motion. No interaction between particles until a collision occurs.

  6. A short flick . . . pass the popcorn

  7. Energy Involved in Phase Changes Liberates Energy Gas Boiling Condensation Liquid Melting Freezing Solid Requires Energy

  8. The ancient Greeks thought that matter was composed of small particles, which they termed atomos, of each of these elements connected (bonded) with each other by the use of small hooks attached to them.kinda like how velcro works . . . .

  9. Laws of Mass Conservation & Definite Proportions (Composition) Law of Mass Conservation: The total mass of substances does not change during a chemical reaction. Law of Definite ( or constant ) Composition: No matter what its source, a particular chemical compound is composed of the same elements in the same parts (fractions) by mass.

  10. Figure 2.2: John Dalton Source: Manchester Literary & Philosophical Society

  11. Mass of Oxygen that Combines with 1.00g of Carbon Compound #1 1.33g Compound #2 2.66g

  12. Law of Multiple Proportions If elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbers: Example: Nitrogen Oxides I & II Nitrogen Oxide I : 46.68% Nitrogen and 53.32% Oxygen Nitrogen Oxide II : 30.45% Nitrogen and 69.55% Oxygen in 100 g of each Cpd: g O = 53.32 g & 69.55 g g N = 46.68 g & 30.45 g g O /g N = 1.142 & 2.284 2.284 2 = 1.142 1

  13. Mass of Nitrogen that Combines with 1.00g of Oxygen Compound #1 1.750 g Compound #2 0.8750 g Compound #3 0.4375 g I1.7502 Cpd #1 N2O NO N4O2 II 0.8750 1 II0.87502 Cpd #2 NO or NO2 or N2O2 III 0.4375 1 I 1.7504 Cpd #3 NO2 NO4 N2O4 III 0.4375 1 = = =

  14. Dalton’s Atomic Theory Postulates: 1. Each element is made up of tiny particles called atoms. 2. The atoms of a given element are identical; the atoms of different elements are different in some fundamental way or ways. 3. Chemical compounds are formed when atoms combine with each other. A given compound always has the same relative numbers and types of atoms. 4. Chemical reactions involve reorganization of the atoms – changes in the way they are bound together. The atoms themselves are not changed in a chemical reaction.

  15. Figure 2.3 (P19): Combining gases on a Molecular Level

  16. Avogadro’s Hypothesis At the same temperature and pressure, equal volumes of different gases contain the same number of particles (Molecules).

  17. Cannizzaro’s Relative Atomic(Molecular) Masses of Carbon and Hydrogen Compound Relative Percent Carbon Relative mass of Molecular Mass by Mass Carbon Present Methane 16 75 12 Ethane 30 80 24 Propane 44 82 36 Butane 58 83 48 Carbon Dioxide 44 27 12 Compound Relative Percent Hydrogen Relative mass of Molecular Mass by Mass Hydrogen Present Methane 16 25 4 Ethane 30 20 6 Propane 44 18 8 Butane 58 17 10

  18. Comparison of Several of Berzelius’s Atomic Masses with Current Values Element Atomic Mass Berzelius’s Value Current Value Chlorine 35.41 35.45 Copper 63.00 63.55 Hydrogen 1.00 1.01 Lead 207.12 207.2 Nitrogen 14.05 14.01 Oxygen 16.00 16.00 Potassium 39.19 39.10 Silver 108.12 107.87 Sulfur 32.18 32.07

  19. A cathode-ray tube. The fast-moving electrons

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