Investigation 7B

1. Investigation 7B The Geometry of Molecules

2. Structural diagram: This molecule looks like it should be “straight” or linear… H O H … but it really has a bent shape Why isn’t water a linear molecule? Investigation 7B: The Geometry of Molecules

3. Structural diagram: This molecule looks like it should be “straight” or linear… H O H … but it really has a bent shape Lone electron pairs on the oxygen atom take up space too! Investigation 7B: The Geometry of Molecules

4. Part 1: Linear and bent molecules Build these five molecules. Compounds made of only 2 atoms are typically bent in shape. Compounds made of only 3 atoms are typically linear in shape. Investigation 7B: The Geometry of Molecules

5. Part 1: Linear and bent molecules • Name two other elements which would likely form a bent molecule when bound with two hydrogen atoms. • Create two other linear molecules. What elements do they contain? Investigation 7B: The Geometry of Molecules

6. Real molecules are not flat but have 3-dimensional forms. Investigation 7B: The Geometry of Molecules

7. Part 2: Trigonal planar and trigonal molecules Build the following molecules. Do these two molecules have the same shape? Investigation 7B: The Geometry of Molecules

8. Part 2: Trigonal planar and trigonal molecules • Which of these molecules has a trigonal pyramidal shape? Can you explain why? • Which of these molecules has a trigonal planar shape? Can you explain why? • Name another element which would combine with three hydrogen atoms to make a trigonal molecule. Investigation 7B: The Geometry of Molecules

9. Part 2: Trigonal planar and trigonal molecules Investigation 7B: The Geometry of Molecules

10. 1s22s22p2 4 valence electrons Carbon Lewis dot diagram for carbon Carbon can donate 4 electrons… Investigation 7B: The Geometry of Molecules

11. 1s22s22p2 4 valence electrons Carbon Lewis dot diagram for carbon Carbon can donate 4 electrons…… or gain 4 electrons. Investigation 7B: The Geometry of Molecules

12. Part 3: Molecules with hydrogen and carbon Build the following molecules. Investigation 7B: The Geometry of Molecules

13. Part 3: Molecules with hydrogen and carbon • Which of these molecules (if any) is planar? • Which of these molecules (if any) is linear? • Which of these molecules (if any) is tetrahedral? A tetrahedron is a pyramid with four triangular sides. • Which of these molecules (if any) is a ring? Investigation 7B: The Geometry of Molecules

14. Part 4: Molecules with nitrogen and oxygen Many important molecules contain nitrogen and oxygen atoms. Investigation 7B: The Geometry of Molecules

15. Part 4: Molecules with nitrogen and oxygen Many important molecules contain nitrogen and oxygen atoms. • Name two instances in these molecules where you find a tetragonal form. What element is central to this form? • Name two instances in these molecules where you find a trigonal form. What element is central to this form? Investigation 7B: The Geometry of Molecules

16. Part 4: Molecules with nitrogen and oxygen Many important molecules contain nitrogen and oxygen atoms. c. Describe what is similar between methanol (wood alcohol) and ethanol (grain alcohol). Investigation 7B: The Geometry of Molecules

17. Part 4: Molecules with nitrogen and oxygen Many important molecules contain nitrogen and oxygen atoms. d. Amines are nitrogen-bearing compounds, often with very strong odors. Which of these compounds are amines? Investigation 7B: The Geometry of Molecules

18. The function of a molecule depends on its 3-dimensional shape. Ascorbic acid (vitamin C) Acetaminophen (active ingredient in Tylenol) Investigation 7B: The Geometry of Molecules