Name: __________________________________ Teacher: ________________________________ Class: __________________________________ Date: ___________________________________ Odor Molecules Introduction Previously in class you created a model of the atoms and molecules that compose air. You learned that oxygen is an element. That means it is made only of oxygen atoms. Other particles that make up air are not elements. They are made of different types of atoms bonded together to form molecules. Carbon dioxide is a molecule that is made of two different types of atoms— carbon atoms and oxygen atoms. There are many more substances found in the air around you. One of these is odor. Part 1: Compare and Contrast (Answer all questions in complete sentences) Look at the models of two different odor molecules. 1. What are some similarities between these 2 odor models? 2. What are some differences between these 2 odor models? 3. What did you notice about the types of atoms each molecule is made of? Part 2: Prediction (Answer in complete sentences) Would you expect substances made of the same types of atoms to have similar or very different odors? Explain your ideas. Part 3: Reading ­ Why do substances have different odors? You probably did not know that there is a Smell and Taste Research Foundation in the United States where scientists study humans’ sense of smell. One scientist, for example, has learned that the smell of peppermint can help athletes perform better. People work out differently when they smell peppermint. They work out longer and harder. Scientists know, too, that the effect also depends on whether a person likes an odor. Green apple odor can help with migraine headaches. However, it might not be helpful to someone who does not like the scent of green apples. Some people smell lavender to make them feel more relaxed. Many people burn scented candles or use air fresheners to put an odor they like into the air. Can you imagine other ways that odors could be helpful? For example, what if you could smell a scent that would help you wake up in the morning? Because scientists learn about the atoms and molecules that make up odors, they can then manipulate odors to benefit other people. What Makes One Odor Smell Different from Another Odor? The substances you have smelled in class had different odors, so you know that they must be different substances. If two substances are different, then either A. the type of atoms they are made of are different, B. the numbers of each type of atom are different, or C. the atoms are connected to each other in different ways. Look at the models of the odors from Part 1 of this activity. Odor 1 is a substance called linalool, which is a molecule found in lavender oil. Odor 2 is a substance called menthol, which is a molecule found in peppermint oil. When you think about how lavender and peppermint smell, do they have similar or different odors? Explain your answer. You cannot actually see molecules of any kind. You cannot see them with your naked eye, with a magnifying lens, or even with the microscopes here at school. When you hold a tiny bit of a substance, such as menthol, you are holding billions of menthol molecules. Part 4: Conclusion (Answer all questions in complete sentences) 1. What substance is odor 1? 2. What substance is odor 2? 3. What are 3 ways substances can differ from each other? 4. How does your prediction compare with what you’ve learned about each odor? 5. Why do you think Odor 1 and Odor 2 have different smells? (Hint: Think about your answer in question #3) 6. If you were a scientist, what use would you try to create for an odor? (Example: what if you could smell a scent that would help you wake up in the morning?)