Smells Unit

1. Smells Unit Investigation II: Picturing Molecules

2. Smells Unit � Investigation II Lesson 1: Molecules in Two Dimensions

3. Unit 2 � Investigation II ChemCatalyst Here are drawings of two molecules that you�ve already smelled. List at least three differences and three similarities between the two molecules.

4. Unit 2 � Investigation II The Big Question Can the structural formula of a molecule help us to predict how it will smell?

5. Unit 2 � Investigation II You will be able to: Describe a molecule based on its smell.

6. Unit 2 � Investigation II A structural formula is a drawing or diagram that a chemist uses to show how the atoms in a molecule are connected. Chemists refer to the connections between atoms in a molecule as a bond. In structural formulas, the covalent bonds are represented as lines.

7. Unit 2 � Investigation II Activity Purpose: In this lesson you are introduced to the structural formulas of the molecules you have smelled plus some new molecules. You will look for patterns in the ways the atoms are connected.

8. Unit 2 � Investigation II Making Sense What structural features seem to be the best predictors of the smell of a molecule?

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10. Unit 2 � Investigation II Functional groups are structural features that show up repeatedly in molecules and seem to account for some of their chemical properties.

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12. Unit 2 � Investigation II Check-In If a molecule is sweet, what other things do you know about it? List at least four things that are probably true.

13. Unit 2 � Investigation II Wrap-Up Structural formulas show how the atoms in a molecule are put together. Certain structural features in molecules called functional groups appear to be related to smell.

14. Smells Unit � Investigation II Lesson 2: Honk If You Like Molecules

15. Unit 2 � Investigation II ChemCatalyst Examine the following molecules. What patterns do you see in the bonding of hydrogen, oxygen, carbon, and nitrogen?

16. Unit 2 � Investigation II The Big Question How can HONC 1234 help us to draw structural formulas?

17. Unit 2 � Investigation II You will be able to: Determine whether the structural formula of a given molecule is possible.

18. Unit 2 � Investigation II HONC 1234 is a simple, catchy phrase reminding us about the bonding of hydrogen, oxygen, nitrogen and carbon. This easy-to-remember phrase reminds us how many bonds each element usually makes within a molecule.

19. Unit 2 � Investigation II Double bonds and triple bonds still follow the HONC 1234 rule. The double-bonded oxygen in the menthone molecule is bonded twice to carbon and therefore follows the guidelines.

20. Unit 2 � Investigation II Activity Purpose: The purpose of this activity is to give you practice in creating structural formulas from molecular formulas and to help you begin to understand why atoms end up in the specific arrangements we find them in.

21. Unit 2 � Investigation II Molecular formula #1 � C3H8 Molecular formula #2 � C3H8O Molecular formula #3 � C3H9N

22. Unit 2 � Investigation II Making Sense The third molecular formula has at least three possible structures. Are these all the same molecule? Explain.

23. Unit 2 � Investigation II Molecular formula #1 (the same molecule drawn with two different orientations)

24. Unit 2 � Investigation II Molecular formula #2 (four different drawings are shown � three different molecules are represented)

25. Unit 2 � Investigation II Molecular formula #3 (four different drawings are shown � however, they represent only three different structures)

26. Unit 2 � Investigation II Molecules are isomers of one another if they have the same molecular formula but different structural formulas.

27. Unit 2 � Investigation II Check-In Are the following molecules correct according to HONC 1234? If not, what specifically is wrong with them? 1. 2.

28. Unit 2 � Investigation II Wrap-Up The HONC 1234 rule tells us how many times hydrogen, oxygen, nitrogen and carbon tend to bond. When a molecule is oriented differently in space it is still the same molecule. A molecular formula can be associated with more than one distinct structural formula.

29. Smells Unit � Investigation II Lesson 3: Connect the Dots

30. Unit 2 � Investigation II ChemCatalyst This is a drawing of the structural formula of a methane molecule. The lines represent bonds. Explain what you think a bond is.

31. Unit 2 � Investigation II The Big Question How can Lewis dot symbols help us to understand and predict bonding?

32. Unit 2 � Investigation II You will be able to: Draw the Lewis dot symbol for an element and predict how many covalent bonds it will make.

33. Unit 2 � Investigation II A covalent bond is a connection that forms between two atoms when those atoms are sharing a pair of electrons between them.

34. Unit 2 � Investigation II When we draw an atom using dots to represent the valence electrons it is called a Lewis dot symbol. When we draw a molecule using dots to represent the valence electrons it is called a Lewis dot structure.

35. Unit 2 � Investigation II Nitrogen, with five valence electrons, would be drawn as follows:

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37. Unit 2 � Investigation II Activity Purpose: In this lesson you will begin to understand why atoms connect to each other the way they do. You will be introduced to a tool, called Lewis dot symbols, which will assist you in building molecules and predicting how many bonds an element will have.

38. Unit 2 � Investigation II C N O F Ne Si P S Cl Ar

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41. Unit 2 � Investigation II Making Sense Based on what you�ve learned in this lesson, explain why the HONC 1234 rule works.

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43. Unit 2 � Investigation II Bonded pair refers to a pair of electrons that are involved in bonding between two different atoms. Lone pair refers to a pair of electrons that are not involved in bonding but are paired up within an atom. A single electron is sometimes referred to as an unpaired electron.

44. Unit 2 � Investigation II Check-In Draw the Lewis dot symbol for the element I, iodine. Explain how you arrived at your particular drawing. How many covalent bonds does iodine make?

45. Unit 2 � Investigation II Wrap-Up A covalent bond is one in which two atoms share valence electrons. In a Lewis dot structure, pairs of electrons that are not bonded are referred to as lone pairs. HONC 1234 indicates how many unpaired electrons are associated with hydrogen, oxygen, nitrogen and carbon.

46. Smells Unit � Investigation II Lesson 4: Eight is Enough

47. Unit 2 � Investigation II ChemCatalyst Draw the Lewis dot structure for the following covalently bonded molecule. Explain how you arrived at your answer. Cl2

48. Unit 2 � Investigation II The Big Question How can we use Lewis dot structures to help draw structural formulas?

49. Unit 2 � Investigation II You will be able to: Predict whether a given compound would be stable and likely to be found in nature.

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51. Unit 2 � Investigation II Activity Purpose: In this lesson you will use Lewis dot structures to create structural formulas of molecules containing elements in addition to H, O, N, and C. You will look for patterns in the number of electrons surrounding each atom in a Lewis dot structure in order to develop further understanding of bonding.

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54. Unit 2 � Investigation II Making Sense The noble gases do not form bonds with other atoms (except under very extreme conditions). Explain why you think this might be true (use your Lewis dot structures).

55. Unit 2 � Investigation II Atoms of most elements are very reactive. They become stable (the opposite of reactive) when they combine with other atoms to form compounds. The more stable a molecule is, the more likely we are to find that it exists in nature. The octet rule states that atoms tend to form bonds by sharing valence electrons until eight valence electrons surround each atom.

56. Unit 2 � Investigation II Check-In Which of the following formulas satisfy the HONC 1234 rule? Which of the following formulas satisfy the octet rule? Which of the following formulas represent stable compounds we might find in the world around us? a) CH3 b) CH4

57. Unit 2 � Investigation II Wrap-Up Elements form bonds by sharing electrons until each atom has the same number of valence electrons as the noble gas in the same row of the periodic table � this is called the octet rule.

58. Smells Unit � Investigation II Lesson 5: Dots, Dots, and More Dots

59. Unit 2 � Investigation II ChemCatalyst Here are the structural formulas for N2 (nitrogen gas), O2 (oxygen gas), and F2 (fluorine gas). Draw the Lewis dot structures for these three molecules.

60. Unit 2 � Investigation II The Big Question How do we draw a Lewis dot structure for a molecule?

61. Unit 2 � Investigation II You will be able to: Use Lewis dot symbols to draw a possible structure for a C2H4O2 molecule.

62. Unit 2 � Investigation II Draw Lewis dot symbols for C and two O atoms: Bring atoms together: Create double bonds:

63. Unit 2 � Investigation II Activity Purpose: In this lesson you will work to create structural formulas for various molecules. You will start with the Lewis dot structures of individual atoms. These atoms can then be arranged in more than one way to create molecules. Finally, structural formulas will be translated from the Lewis dot representations.

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65. Unit 2 � Investigation II Making Sense Explain how HONC 1234 assists you in checking out the structural formulas you create.

66. Unit 2 � Investigation II Check-In We know two things about a certain molecule. We know that its molecular formula is C2H4O2 and we know that it has one C=O in it. Using Lewis dot symbols and the octet rule to guide you, draw at least one possible structure for this molecule. (There are a total of three possible.)

67. Unit 2 � Investigation II Wrap-Up Atoms can form double and triple bonds to satisfy the octet rule.

68. Smells Unit � Investigation II Lesson 6: Where�s the Fun?

69. Unit 2 � Investigation II ChemCatalyst The following two molecules have the same molecular formula, C8H16O2. They also have similar properties. How are their structural formulas similar? How are their structural formulas different?

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71. Unit 2 � Investigation II The Big Question How are molecular structure and molecular properties related?

72. Unit 2 � Investigation II You will be able to: Identify some common functional groups in a large molecule.

73. Unit 2 � Investigation II Activity Purpose: The structure of a molecule determines its properties. Even slight changes in structure can result in significant changes in property. In this activity you will be asked to examine the relationships between the structures and properties of a specific set of molecules. From these data you should be able to predict the properties of new molecules based on their structures alone.

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76. Unit 2 � Investigation II Making Sense 1. What kinds of molecular features did you use to predict the boiling point and smell of these five molecules? 2. What molecular features did the following molecules have in common? a) Molecules that smell fishy b) Molecules that smell putrid c) Molecules with a boiling point range of 49-69 degrees

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78. Unit 2 � Investigation II Check-In Group the following molecules according to their smell. a. Which ones will have similar smells? b. What smells would you predict for the groups and why?

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80. Unit 2 � Investigation II Wrap-Up Molecules with the same functional groups have similar boiling points as well as similar smells. The structural features of a molecule are largely responsible for the chemical behavior of the molecule.

81. Smells Unit � Investigation II Lesson 7: Create a Smell

82. Unit 2 � Investigation II ChemCatalyst What are some of the starting ingredients you will be using in this lab? Name something you will be doing to the chemicals in this experiment.

83. Unit 2 � Investigation II The Big Question How do chemists create the smells they want in the laboratory?

84. Unit 2 � Investigation II You will be able to: Determine whether two molecules with distinct smells can combine to produce a molecule with a different smell.

85. Unit 2 � Investigation II Activity Purpose: You will be working in the lab to create new smells. Purpose: Today�s lesson is a formal laboratory experiment. You should have read the pre-lab and become acquainted with the experimental procedure before today�s class. You will be working in the lab to create new smells.

86. Unit 2 � Investigation II Safety Precautions: Dress appropriately for a chemistry lab and always wear goggles. There should be NO OPEN FLAMES because the organic chemicals are flammable. Extreme care should be taken when handling 18-M sulfuric acid. It burns the skin and creates holes in clothing. Heating must be done slowly and carefully. When heating is finished, hot plates should be turned off immediately. During clean-up place the final products in designated waste containers.

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89. Unit 2 � Investigation II Making Sense What functional group do you think is present in the final molecules? Explain. What do you think happened to the molecules to change the smell?

90. Unit 2 � Investigation II Check-In No Check-In.

91. Unit 2 � Investigation II Wrap-Up Two molecules with distinct smells can combine to produce a new molecule(s) with a different smell.

92. Smells Unit � Investigation II Lesson 8: Making Scents

93. Unit 2 � Investigation II ChemCatalyst What do you think happened in yesterday�s experiment to transform an acid molecule and an alcohol molecule into a sweet smelling molecule?

94. Unit 2 � Investigation II The Big Question What happened in the test tubes to create new substances?

95. Unit 2 � Investigation II You will be able to: Predict the product of a chemical reaction.

96. Unit 2 � Investigation II A chemical reaction (rxn) is defined as a chemical transformation or change that occurs when substances interact to produce new substances with new properties. A chemical reaction is the same as a chemical change. The starting ingredients in a chemical reaction are called the reactants. The ending compounds are called the products.

97. Unit 2 � Investigation II When chemists show the reactants and the products in a chemical sentence like this:it is called a chemical equation. A catalyst is a substance added to a reaction that accelerates that chemical reaction but is not itself consumed or altered by the reaction.

98. Unit 2 � Investigation II Activity Purpose: This lesson will assist you in processing and making sense of the experiment you just completed. By examining the structural formulas of the starting ingredients, you will be able to see how the molecules broke apart and recombined to create the sweet-smelling products.

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104. Unit 2 � Investigation II Making Sense Use your own words to describe what you think happened on a molecular level to the two compounds that took part in this reaction.

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106. Unit 2 � Investigation II Check-In Predict the structural formula of the product of the following reaction. What is missing from the equation? What smell would you expect? Could you figure out the name of the product?

107. Unit 2 � Investigation II Wrap-Up The smell of the molecules in the ester lab changed because the reactant molecules combined to form different molecules.