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Module 2 Intro

1. Module 2 Intro

1.11. Page 3

Lesson 2

Module 2—Chemical Compounds

Reflect and Connect

 

Discuss

 

Answer one of the following questions. Post your answers to your class discussion area so that you can share and read ideas from others in your class. Your answer to the second question will consider the influence that shape has on the function of a molecule.

  1. VSEPR is an abbreviation for valence shell electron pair repulsion. Which word, or words, from the title do you feel are most significant in identifying how this theory can be used to predict molecular shapes? Justify your answer.

    Post your answer to your class discussion area. Read the postings from other students. Did most of the students select the same word you did? Were students able to justify their choices by using examples or adequate descriptions?

    Before you complete this question, you may wish to take the opportunity to revise your answer by adding detail to the justification you wrote. Place a copy of your completed work in your course folder.

A photograph of a mosquito coil. Composed of a long thin rectangular strip wrapped into a flat coil. The coil is supported by a small metal holder.

© Lai Leng Yiap/iStockphoto

  1. Many strategies are used to confuse mosquitoes and prevent their feeding during summer outdoor activities. DEET is a common component of insect repellents. The chemical structure of DEET is shown below.

A chemical structure for the DEET molecule. The molecule consists of a hexagon shape formed from carbon atoms. This is connected to a five atom structure by a one-carbon bridge. The hexagon shape has a carbon atom at each point. Each carbon atom forming the ring is bonded to one hydrogen atom. The ring has three double bonds, between the first and the second carbon atoms, the third and the fourth carbon atoms, and the fifth and the sixth carbon atoms. The first carbon atom in the ring is labelled “1”. The second atom in the ring is connected to a carbon atom that has a double bond to an oxygen atoms, and a bond to a nitrogen atom. The carbon atom with the double bond to the oxygen is labelled “2”. The nitrogen atom has two additional bonds, each to 2 carbon chains. The first carbon in the chain is bonded to two hydrogens, and the second carbon is bonded to three hydrogens. The nitrogen atom is labelled “3”. The last carbon atom in the two-carbon chain is labelled “4”.

 


  1. Determine the stereochemical shape of the molecule at each of central atoms labelled 1, 2, 3, and 4 in the diagram. If you wish to build a model of the DEET molecule, follow the instructions on the handout “Representing Atoms Using Models” that you printed earlier in the lesson.

  2. DEET is believed to act by confusing a mosquito’s sense of smell. Evidence shows that DEET blocks the mosquito’s sense receptors that detect the molecule 1-octen-3-ol, which is present in human sweat. If sense receptors rely on molecular shape to be stimulated, comment on the shape of the DEET molecule as compared to 1-octen-3-ol. Suggest how this information could be used to develop other insect repellents.

Submit a copy of your answer to question 2 to your teacher. Use any comments you receive from your teacher to revise your work on this question and on any other questions in this lesson and module.

 

Module 2: Lesson 2 Assignment

 

Retrieve the copy of the Module 2: Lesson 2 Assignment that you saved to your course folder earlier in this lesson. Complete all the questions in the assignment.

 

Save a copy of the completed assignment to your course folder. Submit a second copy of your completed assignment to your teacher.