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Chemistry

Chemistry. T he Science of Matter. Do Now. List at least 5 chemicals that you are familiar with from past experience. Learning Objective. Understand composition and their impact on the properties of matter Be able to classify chemical vs. physical changes. Chemistry.

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Chemistry

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  1. Chemistry The Science of Matter

  2. Do Now • List at least 5 chemicals that you are familiar with from past experience.

  3. Learning Objective • Understand composition and their impact on the properties of matter • Be able to classify chemical vs. physical changes

  4. Chemistry • The science that investigates the structure and properties of matter • Matter: anything that takes up space and has mass • Mass: the measure of the amount of matter that an object contains • NOT Matter- • Heat • Light • Radio waves etc.

  5. Matter continued • Structure: refers to what it is made of and of how it is organized • Properties: Describe the characteristics and behavior of matter including the changes it undergoes

  6. Behavior of Matter • Determined by BOTH • The elements it contains • Arrangement of those elements

  7. Example Salt vs. Water Sodium and Chloride Hydrogen and Oxygen Contain different elements --- Have different properties!

  8. Example • Aspirin Vs Table Sugar • Both contain only Carbon, Hydrogen and Oxygen molecules --- same composition • Different Structures Cause Different Behaviors!

  9. Example Two Different Artificial Sweeteners Aspartame Saccharine Different Compositions Both have: C, H, O and N and are sweet Only Saccharine has Na+ and S Their arrangement must be a factor!

  10. Properties • Many are easy to observe by simple tests • Use heat, magnets, electricity etc • Color • State: solid, liquid or gas at room temp and pressure • Soft or hard • Does it burn? • Does it dissolve in water? • These are from a macroscopic perspective • Things you can touch, taste, feel, smell and see

  11. What is it made of? • This question is harder to answer • Must take measurements • Must observe chemical changes • Macroscopic Observations • Submicroscopic perspective • To understand hidden structure influences behavior

  12. Physical change vs. Chemical change

  13. Examples

  14. Physical Vs. Chemical Change Worksheet (15 minutes) • In pairs complete the given handout • You may use your notes • Students should each complete an answer sheet as a study guide • Be sure that you are prepared to share your answers with the class

  15. Share Answers

  16. Chemical properties vs. Physical properties • Chemical Property • Flammability: The ability to burn • Ability to rust:Reacts with oxygen to produce rust • Reactivity with vinegar: Reacts with vinegar to produce new substances • Physical Property • Transparency: The property of letting light pass through something • Boiling point: Temperature at which a substance goes from liquid to gas • Melting point: Temperature at which a substance goes from solid to a liquid • Brittleness: Tendency to crack or break • Ductility: Ability to bend without breaking • Elasticity: Ability to be stretched or compressed then return to original size • Density: Mass per unit volume

  17. Submicroscopic Level of Matter • Matter is made of Atoms • Atoms • So small they can not be seen with the most powerful light microscope • So small that if a period at the end of a sentence were made of Carbon atoms it would be made of 100 quintillion carbon atoms • (100, 000,000,000,000,000,000) • Counting them at 3 per second would take you a trillion years! • Scanning Tunneling Microscope (STM) • creates computer images which are a visible perspective showing atomic location

  18. Scanning Tunneling Microscope (STM) • individual iron atoms on a silver substrate

  19. Using Chemical Models • Show types and numbers of atoms • Show arrangement of the atoms and space filled

  20. Why Models? • Submicroscopic structural representation • Explains observed behavior • Used to predict behavior not yet observed • Built on investigation and experimentation

  21. Show Connections Between Atoms

  22. Mixtures • A material that is made of 2 or more things which are not combined chemically • Each of the parts still keep their own identities • Made by blending, but NOT forming chemical bonds or chemical change! • Most everyday matter occurs as mixtures

  23. Heterogeneous and Homogeneous Mixtures • A classification of matter based on composition • Homogeneous mixture: no clumping or grouping but rather a uniform dispersal of the material it is made of. • Ex. Air; made of N2, O2, CO2 and other gases • A liquid in which there is a solvent and a solute is called a solution • Heterogeneous mixture: it is easy to identify all if the different components

  24. Heterogeneous mixture

  25. Heterogeneous mixture

  26. Colloids (look homogeneous but microscopically heterogenous) • Hair spray • Smoke • Cloud • Whipped cream • Shaving cream • Blood • Styrofoam • Gello

  27. Dispersion (Heterogeneous) • Dust • Milk • Hand cream • Gravel • Granite • Sponge

  28. Homogeneous Mixtures

  29. Solutions (homogeneous) • Air (gas) • Martini (liquid) • Salt water (liquid) • Plastic (solid)

  30. Substances • Homogeneous materials that contain only 1 kind of matter • Have definite composition and properties • Substances which can not be broken down into a simpler substance is an ELEMENT. • Substances which can be broken down into a simpler substance is a COMPOUND. • They are made of 2 or more elements

  31. Elements • Made of only one kind of atom • Can not be made simplified by physical or chemical means • Can exist as atoms (carbon) or molecules (N2)

  32. Compounds • Consist of 2 or more DIFFERENT atoms bound together (H2O) • Can be broken down into smaller types of matter by chemical means only. • Have properties which are different than the elements they are made of • Always contain the same ratio of its components atoms ( ex 2 hydrogen's to 1 oxygen, in water)

  33. Answers to pg 7 questions • Ocean water- solution • Calcium- element • Vitamin C- Compound ( L-asorbic acid) • Dry ice – compound (CO2) • Copper- element • Grain alcohol- compound (C2H5OH) • after shave lotion- heterogenous mixture • Hamburger- hetero • Al foil – element • Milk- solution • Salt- cmpd • Iron nail- element

  34. Learning Objectives • Investigate various ways to separate mixtures • Identify the properties of the matter that allow for a particular method of separation

  35. REMEMBER Mixtures • A remade of 2 or more things which are not combined chemically • Each of the parts still keep their own identities • Made by blending, but NOT forming chemical bonds or chemical change! • Most everyday matter occurs as mixtures

  36. REMEMBERChemical properties vs. Physical properties • Chemical Property • Flammability: The ability to burn • Ability to rust:Reacts with oxygen to produce rust • Reactivity with vinegar: Reacts with vinegar to produce new substances • Physical Property • Transparency: The property of letting light pass through something • Boiling point: Temperature at which a substance goes from liquid to gas • Melting point: Temperature at which a substance goes from solid to a liquid • Brittleness: Tendency to crack or break • Ductility: Ability to bend without breaking • Elasticity: Ability to be stretched or compressed then return to original size • Density: Mass per unit volume

  37. Separating Mixtures • Mixtures can be separated through a physical process, the identity of the substance remains unchanged. • Using their Physical properties • Bringing about physical changes to separate the mixture into its components (different substances it is made of)

  38. Making a Mixture AND SAND SUGAR

  39. The Mixture

  40. How can we separate it? • What do you think? • Work with your lab partner to come up with a suggested method. (10 minutes) • You may use your class notes, but your brain is your best asset. • Write your thoughts in your notebooks. • Do not be afraid to try!

  41. Report out on ideas • So, what did you come up with? • Share your thoughts! (10 minutes)

  42. What can we do? Method #1 Use a pair of tweezers and a microscope to physically separate the particles Requires a lot of time and patience

  43. Method #2 Step #1 Recall the properties of water and of sand Sugar dissolves in water Sand does NOT Use the difference!

  44. Step #2 Recall the properties again sand will not pass through a filter Sugar and water solution will Use the difference!

  45. Step #3 Recall the properties of sugar and water sugar will not evaporate (change state) at 100 degrees Celsius water will ! Use the difference!

  46. You have the two pure substances again! • Sand in the filter! • Sugar in the bottom of the beaker!

  47. Lab Thursday! • Paper Chromatography!

  48. Learning objective • Understand the relationship between chemical change and energy change

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