Smells Unit

1. Smells Unit Investigation III: Building Molecules Lesson 1: New Smells, New Ideas Lesson 2: Molecules in Three Dimensions Lesson 3: Two’s Company Lesson 4: Let’s Build It Lesson 5: Shape Matters Lesson 6: What Shape Is That Smell? Lesson 7: Sorting It Out

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

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

4. citronellol C10H20O geraniol C10H18O menthol C10H20O (cont.) Unit 2 • Investigation III

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

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

7. 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. (cont.) Unit 2 • Investigation III

8. Unit 2 • Investigation III

9. (cont.) Unit 2 • Investigation III

10. 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. (cont.) Unit 2 • Investigation III

11. SmellsSummary Chart Chemical Name “ine” = fishy Another property of molecules? smell Functional Group amine = fishy Molecular Formula 1 N = fishy Unit 2 • Investigation III

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

13. 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. Unit 2 • Investigation III

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

15. 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. Molecule #1 sweet Unit 2 • Investigation III

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

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

18. Notes (cont.) • 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. Unit 2 • Investigation III

19. 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. (cont.) Unit 2 • Investigation III

20. (cont.) Molecule #1 Sweet smelling (cont.) Unit 2 • Investigation III

21. (cont.) Molecule #2 Minty smelling (cont.) Unit 2 • Investigation III

22. (cont.) Molecule #3 Camphor smelling Unit 2 • Investigation III

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

24. Check-In • List the molecular model pieces you would need to build a model of ethanol—C2H6O. Unit 2 • Investigation III

25. 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. Unit 2 • Investigation III

26. Smells Unit – Investigation III Lesson 3: Two’s Company

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

28. 1. 2. 4. 3. (cont.) Unit 2 • Investigation III

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

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

31. Notes • 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. Unit 2 • Investigation III

32. Notes (cont.) • 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. Unit 2 • Investigation III

33. 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. (cont.) Unit 2 • Investigation III

34. (cont.) • CH4 NH3 H2O Unit 2 • Investigation III

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

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

37. Notes(cont.) CH4 NH3 H2O Unit 2 • Investigation III

38. 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. Unit 2 • Investigation III

39. 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. Unit 2 • Investigation III

40. Smells Unit – Investigation III Lesson 4: Let’s Build It

41. CH4 NH3 H2O HF Ne ChemCatalyst • Remove the lone pair paddles from all five models. Now describe the remaining geometric shape. Unit 2 • Investigation III

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

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

44. tetrahedral pyramidal bent linear point Notes (cont.) Unit 2 • Investigation III

45. Notes(cont.) • 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. (cont.) Unit 2 • Investigation III

46. 3 electron domains A model of a trigonal planarmolecule as seen from above. Notes(cont.) • 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. Unit 2 • Investigation III

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

48. Unit 2 • Investigation III

49. Unit 2 • Investigation III

50. Unit 2 • Investigation III