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Great Ideas in Science: Lecture 6 – Properties of Materials

Great Ideas in Science: Lecture 6 – Properties of Materials. Professor Robert Hazen PROV 301. KEY IDEA: Properties of materials depend on their atoms, and how those atoms are linked together. Tonight ’ s Outline. Review Chemical Bonding Chemical Reactions Properties of Materials

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Great Ideas in Science: Lecture 6 – Properties of Materials

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  1. Great Ideas in Science:Lecture 6 – Properties of Materials Professor Robert Hazen PROV 301 KEY IDEA: Properties of materials depend on their atoms, and how those atoms are linked together

  2. Tonight’s Outline • Review Chemical Bonding • Chemical Reactions • Properties of Materials • States of matter • Changes of state • Strength of materials • Electrical properties

  3. Chemical Bonding Key Idea: Atoms link together by the rearrangement of their electrons 1. “Magic” numbers of electrons (i.e. 2, 10, 18, and 36) form very stable atoms. 2. Electrons may be transferred or shared to form stable bonds. 3. Ionic, metallic, and covalent bonds

  4. Ionic Bonding

  5. Ionic Bonding Ionic Bonding Na Cl

  6. Ionic Bonding

  7. Ionic Bonding

  8. Ionic Bonding Mg + 2Cl MgCl2 Mg + 2Cl

  9. Ionic Bonding Fluorite CaF2

  10. Ionic Bonding Two properties of materials with ionic bonds: 1. Insulates electricity—“insulator” (electrons don’t move) 2. Tough but brittle—cup demo.

  11. Metallic Bonding

  12. Metallic Bonding

  13. Metallic Bonding

  14. Metallic Bonding Three properties of materials With metallic bonds: 1. Conducts electricity—Wire (electrons free to move) 2. Malleable—Coat hanger 3. Shiny

  15. Covalent Bonding

  16. Covalent Bonding Hydrogen

  17. Covalent Bonding

  18. Covalent Bonding WATER

  19. Covalent Bonding

  20. 1 C 4 2 3 (R)-enantiomer Covalent Bonding: Carbon CARBON BONDING Organic Chemistry

  21. 1 C 4 2 3 (R)-enantiomer Covalent Bonding: Carbon CARBON BONDING Organic Chemistry

  22. States of Matter

  23. SOLIDS(fixed volume and shape) Crystal – regular atomic arrangement

  24. SOLIDS(fixed volume and shape) Glass: Atoms not periodic

  25. Glass vs. Crystal Structure

  26. Solids: Plastics Plastics: Formed from chains of molecules

  27. Plastic Recycling

  28. LIQUIDS (fixed volume, variable shape)

  29. LIQUIDS (fixed volume, variable shape) Liquid Crystals: Molecules line up under an electric field

  30. GAS (variable volume and shape)

  31. PLASMA (Gas with free electrons) By far the most abundant state of matter in the universe!!!

  32. Changes of State HYDROCARBONS

  33. Changes of State Gas Liquid Solid How does a candle work?

  34. Distillation (Fractionation) Column Gasoline, kerosene, diesel fuel, asphalt & tar are distilled from crude oil.

  35. Chemical Reactions: Oxidation & Reduction

  36. Chemical Reactions: Oxidation & Reduction Rusting = Oxidation Smelting = Reduction

  37. Chemical Reactions:Acid & Base Reactions

  38. Chemical Reactions:Acid & Base Reactions

  39. Chemical Reactions: Polymerizaton & Depolymerization Addition Polymerization

  40. Chemical Reactions: Polymerizaton & Depolymerization Condensation Polymerization

  41. Materials and the Modern World • Materials define a society’s technical sophistication • Chemists’ contributions • Properties of materials result from: • The kind of atoms of which it is made • The arrangement of those atoms • Type of bonding between those atoms

  42. Different Kinds of Strength • Strength • Compressive • Tensile • Shear • Elastic Limit = the breaking point • Strength depends on the types and arrangements of bonds

  43. Compressive Strength:(Strength against squeezing) • Stack of paper • Masonry • Wood

  44. Tensile Strength:(Strength against pulling) • Wire • Rope • Chains

  45. Shear Strength:(Strength against twisting) • Girder network • Diamond

  46. Composite Materials • Combination of materials increases strength • Reinforced concrete • Fiberglass • Plywood

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