« Return to AACT homepage

AACT Member-Only Content

You have to be an AACT member to access this content, but good news: anyone can join!


Need Help?

Modeling Carbohydrates (4 Favorites)

ACTIVITY in Naming Compounds, Introduction, Interdisciplinary, Molecular Formula, Molecular Structure, Molecular Structure , Chemical Bond. Last updated February 4, 2019.


Summary

In this activity, students will identify that organic compounds contain carbon and other elements such as hydrogen and oxygen. They will investigate the structure of different organic and inorganic compounds and model several molecules, including a carbohydrate molecule. They will use their models to help understand how larger molecules are broken down into smaller molecules.

Grade Level

Middle and High School

Objectives

By the end of this activity, students should be able to

  • Identify an organic compound by its components
  • Recognize how large molecules are broken into smaller molecules

Chemistry Topics

This activity supports students’ understanding of

  • Molecular structure
  • Organic molecules

Time

Teacher Preparation: 20 minutes

Lesson: 45 minutes

Materials (for each group)

  • 24 Gumdrops (3 different colors needed, divided by color into groups of: 12, 6 and 6)
  • Toothpicks
  • Colored pencils

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • When students complete the lab, instruct them how to clean up their materials.
  • Food in the lab should be considered a chemical not for consumption.

Teacher Notes

  • This activity should be completed in small groups of 2-4 students
  • Students should be familiar with valence electrons prior to completing this activity.
  • Remind students the toothpicks represent the bond; H can make one bond, C can make up to 4 bonds, and O can make up to 2 bonds, model correct usage before the activity.
  • Reinforce that organic molecules contain carbon, include examples and non-examples for clarification.
  • Possible modification problems could be: How can scientists model organic compounds?
  • Students can research 3-D models. They can also analyze the importance of chemical energy.

For the Student

Lesson

Background

Large carbohydrate molecules are broken down into smaller molecules in the cell in order to release energy for cell function and growth. Remember that organic molecules contain carbon.

Problem

You will make observations, create models of molecules, and identify the atoms that make up inorganic and organic molecules.

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Wash your hands thoroughly before leaving the lab.
  • Follow your teacher’s instructions for clean-up.
  • Food in the lab should be considered a chemical not for consumption.

Procedure

  1. You will use gumdrop models to show how atoms of different elements bond together to make up a molecule. Gumdrops of different colors will represent carbon, hydrogen, and oxygen. Analyze your gumdrops and plan which color you will use for each type of atom. Hint: You will need the most gumdrops for hydrogen. Record your results in the Results section.
  2. Analyze your materials and decide how you will use them to construct models of molecules using the following structural formulas. Construct each model show below:
Chart
  1. Of the three molecules above, two are organic molecules. Identify which two are organic. What makes these different from the third molecule? Record ideas about how to characterize organic molecules in the Results section.
  2. Notice that there is only one bond between each pair of atoms. These are called single bonds. How many single bonds does each type of atom make? Record your answers in the Results section
Glucose
  1. The structural formula for a glucose molecule is shown above, a simple carbohydrate. How many of each type of atom must you include in a model of glucose? Write the chemical formula of glucose in the Results section.
  2. Using the chemical and structural formulas for glucose use your gumdrops to construct a model. Sketch your model in the Results section.
  3. Plants and animals require glucose and other simple carbohydrates to supply their cells with energy. But sugar molecules in plants and animals are found as part of a carbohydrate molecule, in which glucose molecules bond together forming long chains.
Capture

Organisms must break down carbohydrate molecules into smaller molecules to feed their cells. Glucose molecules themselves are also broken down into smaller molecules to provide energy to cells. How could glucose be broken down into smaller molecules? What kinds of molecules could you make? (hint: photosynthesis) Write the answer in the Results section.

  1. Use your glucose model to form as many of the following smaller molecules as possible: water, H2O (H-O-H) and carbon dioxide, CO2 (O=C=O). Record how many of each you can make in the Results section.

Results

  1. Record the color of the gumdrops you will use for the following elements:
    • Carbon:
    • Hydrogen:
    • Oxygen:
  2. What are ways to characterize organic molecules?
  3. How many single bonds does each type of atom have?
    C:
    O:
    H:
  4. What is the chemical formula for Glucose?
  5. Sketch your model of glucose:
  6. How could glucose be broken down into smaller molecules? What molecules could you make?
  7. How many water molecules did you make?
    How many carbon dioxide molecules did you make?

Conclusion

  1. Explain why do you think it is important that larger molecules can react to become smaller?
  2. Which of the molecules that you constructed in this investigation are considered organic molecules and which are not? Do you think that every molecule that contains carbon is classified as organic? Does any inorganic molecule contain carbon? Explain.