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Smells Unit

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Smells Unit

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    1. Smells Unit Investigation III: Building Molecules

    2. Smells Unit Investigation III Lesson 1: New Smells, New Ideas

    3. Unit 2 Investigation III ChemCatalyst Do you think any of these molecules will smell similar? What evidence do you have to support your prediction?

    4. Unit 2 Investigation III

    5. Unit 2 Investigation III The Big Question How do we refine our hypothesis about how smell works?

    6. Unit 2 Investigation III You will be able to: Evaluate the usefulness of functional groups in predicting the smell of a molecule.

    7. Unit 2 Investigation III Activity Purpose: In this lesson you will be introduced to five new molecules. These molecules will lead you in the direction of new discoveries about the relationship between smell and chemistry.

    8. Unit 2 Investigation III

    9. Unit 2 Investigation III

    10. Unit 2 Investigation III Making Sense Review the results of the smell investigation to date by indicating on the following chart: (1) how molecular formulas can be used to predict smell, (2) how name can be used to predict smell, (3) how functional group can be used to predict smell, (4) what other information might be important. Examples are given for molecules that smell fishy.

    11. Unit 2 Investigation III

    12. Unit 2 Investigation III Check-In No Check-In.

    13. Unit 2 Investigation III Wrap-Up Molecular formula and functional group are not always sufficient information to predict the smell of a molecule accurately. It appears that the overall shape of a molecule may be related to its smell.

    14. Smells Unit Investigation III Lesson 2: Molecules in Three Dimensions

    15. Unit 2 Investigation III ChemCatalyst This is a new way to represent one of the molecules that you smelled in the last class. Which molecule is this? Give your reasoning.

    16. Unit 2 Investigation III The Big Question Why do some molecules with the same functional group have different smells?

    17. Unit 2 Investigation III You will be able to: Name some differences between a structural formula and a ball-and-stick model.

    18. Unit 2 Investigation III A ball-and-stick model is a 3-dimensional model that a chemist uses to show how the atoms in a molecule are arranged in space.

    19. Unit 2 Investigation III Activity Purpose: In this class you will be introduced to 3-dimensional molecular models. These particular molecular models are called ball-and-stick models. This type of model gives us more information than a structural formula. It shows how the atoms in a molecule are arranged in space.

    20. Unit 2 Investigation III

    21. Unit 2 Investigation III

    22. Unit 2 Investigation III

    23. Unit 2 Investigation III Making Sense What information do you need to know about a molecule in order to build a ball-and-stick model of it?

    24. Unit 2 Investigation III Check-In List the molecular model pieces you would need to build a model of ethanolC2H6O.

    25. Unit 2 Investigation III Wrap-Up A ball-and-stick model is a 3-dimensional representation of a molecule that shows us how the atoms are arranged in space in relationship to one another. Molecules have complex 3-dimensional shapes. The atoms are not necessarily lined up in straight lines and molecules are not flat as depicted in a structural formula.

    26. Smells Unit Investigation III Lesson 3: Twos Company

    27. Unit 2 Investigation III ChemCatalyst Here is the structural formula of ethanol. Which is the correct ball-and-stick model for ethanol? Explain your reasoning.

    28. Unit 2 Investigation III

    29. Unit 2 Investigation III The Big Question Why are molecules in a ball-and-stick model crooked rather than straight?

    30. Unit 2 Investigation III You will be able to: Build a ball-and-stick model showing lone pair electrons for a molecule.

    31. Unit 2 Investigation III Electron pairs are sometimes called bonded pairs. Both of these terms are a bit inaccurate because not all covalent bonds consist of a pair of electrons. Electron charge is another area of potential confusion. We cannot fully explain why two particles with identical negative charges remain in such close proximity to one another within a covalent bond.

    32. Unit 2 Investigation III Sets of electrons that remain together in bonds or in lone pairs are referred to as electron domains. Electron domains prefer to be as far apart as possible from each other.

    33. Unit 2 Investigation III Activity Purpose: In this class you will gain practice creating three dimensional models of some small molecules. The concept of electron domains helps to explain why molecules actually exist in crooked and bent shapes, rather than straight lines.

    34. Unit 2 Investigation III CH4 NH3 H2O

    35. Unit 2 Investigation III Making Sense Explain how the lone pairs affect the shape of your molecules.

    36. Unit 2 Investigation III The underlying shape in all three of the molecules we created today is called tetrahedral. A paddle represents a lone pair.

    37. Unit 2 Investigation III

    38. Unit 2 Investigation III Check-In Build a model for HF. Be sure to show all of the lone pairs. Build a model for Ne. Be sure to show all of the lone pairs.

    39. Unit 2 Investigation III Wrap-Up Electron domains represent the space occupied by bonded electrons or a lone pair. Electron domains are located as far apart from one another as possible. The 3-dimensional shape of a molecule is determined by both bonding electrons and lone pairs.

    40. Smells Unit Investigation III Lesson 4: Lets Build It

    41. Unit 2 Investigation III ChemCatalyst Remove the lone pair paddles from all five models. Now describe the remaining geometric shape.

    42. Unit 2 Investigation III The Big Question How do we describe the shape of a large molecule?

    43. Unit 2 Investigation III You will be able to: Predict the shape of a molecule.

    44. Unit 2 Investigation III

    45. Unit 2 Investigation III Lone-pair paddles are not generally included in ball-and-stick models. We have included them in order to illustrate how lone pairs affect molecular shape. A linear molecule has three atoms in a row, with two electron domains around the central atom.

    46. Unit 2 Investigation III A trigonal planar shape is flat and consists of four atoms bonded together in a single plane. The central atom is bonded to three atoms but unlike ammonia there are only three electron domains in these molecules as shown below.

    47. Unit 2 Investigation III Activity Purpose: In this lesson you gain practice creating actual ball-and-stick models from molecular formulas, using Lewis dot structures to assist you.

    48. Unit 2 Investigation III

    49. Unit 2 Investigation III

    50. Unit 2 Investigation III

    51. Unit 2 Investigation III

    52. Unit 2 Investigation III Making Sense

    53. Unit 2 Investigation III Check-In What is the shape of the following molecule? H2S

    54. Unit 2 Investigation III Wrap-Up Knowing the Lewis dot structure of a molecule allows one to predict its 3-dimensional shape. The shape of large molecules is determined by the smaller shapes around individual atoms. While lone pairs affect the positions of the atoms, they are not included in describing the shape of a molecule. The shape refers only to the positions of the atoms.

    55. Smells Unit Investigation III Lesson 5: Shape Matters

    56. Unit 2 Investigation III ChemCatalyst Write chemical formulas for the following two molecules. Are these two representations of the same molecule? Why or why not? Do you expect these two molecules to have similar properties? Why or why not?

    57. Unit 2 Investigation III The Big Question What evidence suggests that chemical properties are related to the shape of a molecule?

    58. Unit 2 Investigation III You will be able to: Name some chemical properties that are related to shape.

    59. Unit 2 Investigation III Activity Purpose: To compare the properties of maleic acid and fumaric acid, two compounds with identical molecular formulas. Safety note: Everyone will wear safety goggles at all times.

    60. Unit 2 Investigation III

    61. Unit 2 Investigation III

    62. Unit 2 Investigation III Making Sense What evidence do you have that molecular shape is related to chemical properties?

    63. Unit 2 Investigation III The H atoms on the C atoms on either side of the double bond can both point in the same direction or they can point in opposite directions. These two forms are called isomers. The form with both H atoms pointing in the same direction is referred to as the cis isomer. When the H atoms point in opposite directions, the isomer is referred to as a trans isomer.

    64. Unit 2 Investigation III Check-In No Check-In.

    65. Unit 2 Investigation III Wrap-Up Chemical properties are related to shape. Twisting (or rotation of) the ends of a molecule around a C=C double bond is restricted. Isomers are molecules with the same chemical formula but different shapes.

    66. Smells Unit Investigation III Lesson 6: What Shape Is That Smell?

    67. Unit 2 Investigation III ChemCatalyst What obvious differences do you see between these two different types of models?

    68. Unit 2 Investigation III The Big Question Is there a relationship between the 3-dimensional shape of a molecule and its smell?

    69. Unit 2 Investigation III You will be able to: Discuss how the three-dimensional model of a molecule relates to its structural formula.

    70. Unit 2 Investigation III A space-filling model is a 3-dimensional model that a chemist uses to show how the atoms are arranged in space and how they fill this space.

    71. Unit 2 Investigation III Activity Purpose: In this lesson you will be introduced to space-filling models of six molecules. By comparing and contrasting these models, you will learn more about the relationship between smell and chemistry.

    72. Unit 2 Investigation III

    73. Unit 2 Investigation III

    74. Unit 2 Investigation III Making Sense On the basis of your examination of these space-filling models, do you think there is a connection between molecular shape and smell? Provide evidence for your answer.

    75. Unit 2 Investigation III These three larger shapes are referred to as stringy, flat, and ball-shaped. Sweet smells are associated with stringy molecules, minty smells are associated with flat molecules, and camphor smells are associated with ball-shaped molecules.

    76. Unit 2 Investigation III Check-In What smell do you predict for the substance in Vial V? Explain your reasoning.

    77. Unit 2 Investigation III

    78. Unit 2 Investigation III A pheromone is a chemical substance that is produced by an animal and serves as a form of chemical communication to other individuals of the same species, often stimulating specific behavioral responses. It is called an aggregation pheromone because it causes large numbers of insects to collect in one place.

    79. Unit 2 Investigation III Wrap-Up Space-filling models provide another way of looking at the 3-dimensional shape of moleculesone that represents the space occupied by atoms. Smell appears to be directly related to the 3-dimensional molecular shape of a substance.

    80. Smells Unit Investigation III Lesson 7: Sorting It Out

    81. Unit 2 Investigation III ChemCatalyst What smell(s) do you predict for a stringy molecule? Explain your reasoning.

    82. Unit 2 Investigation III The Big Question What chemical information is most useful in predicting smell?

    83. Unit 2 Investigation III You will be able to: Predict the smell of a mystery molecule.

    84. Unit 2 Investigation III Activity Purpose: In this lesson you will try to determine which pieces of chemical information are most valuable in determining the smell of a molecule. You will examine information on all of the smell molecules youve encountered so far, in order to come up with specific relationships between chemical information and the five smell categories.

    85. Unit 2 Investigation III

    86. Unit 2 Investigation III Making Sense In what ways are shape, functional group, and molecular formula related to smell?

    87. Unit 2 Investigation III Sweet: Minty: Camphor: Fishy: Putrid:

    88. Unit 2 Investigation III Check-In Write down the number on your Mystery Card. Predict the smell of the mystery molecule. Explain your reasoning.

    89. Unit 2 Investigation III Wrap-Up Molecular shape can be used to predict smells for esters, alcohols, ketones, and aldehydes. Amines and carboxylic acids have distinctive smells. For stringy molecules it is necessary to look at functional group as well as molecular shape in order to determine smell.

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