Step 2: Review the chemical reaction. a) The chemical reaction that you will model is shown below. Calcium oxide (CaO) is a white solid with a crystalline structure. It is made by heating limestone, coral, sea shells, or chalk, which are composed mainly of calcium carbonate (CaCO3). During the heating process, carbon dioxide (CO2) is released and calcium oxide (CaO) is produced. Commercially, calcium oxide is called lime. One of the oldest uses of lime is to make mortar, a substance used in construction to secure bricks, stones, and blocks together.
CaCO3  CaO + CO2
Student Guide (continued)
Step 3: Build a model of the reactant.
a) Use gumdrops and toothpicks to build a model of CaCO3.
b) Select one color of gumdrop for calcium, a second color for carbon, and a third color for
oxygen. Be sure to include a key of your chosen color scheme with your model.
c) Use the periodic table to help you determine the number of bonds each atom will form.
Step 4: Build models of the products.
a) Use gumdrops and toothpicks to build a model of CaO and a model of CO2.
b) Be sure to use the same colors of gumdrops for calcium, carbon, and oxygen as you did in
Step 3. Include a key of your chosen color scheme with your models.
c) Use the periodic table to help you determine the number of bonds each atom will form.
Step 5: Type one to two paragraphs that describe your models and explain the conservation of mass in the chemical reaction.
a) Create a new blank document. Type your name at the top.
b) Type one to two paragraphs that describe your models and relate them to the law of conservation of mass. Your document should:
i. identify the names of the reactants and products in the reaction.
ii. identify the number of molecules that make up the reactants and products.
iii. identify the type and number of atoms in each molecule of the reactants and products.
iv. explain what happens during the chemical reaction.
v. explain how mass is conserved during the chemical reaction.
Step 6: Evaluate your project using this checklist.
If you can check each criterion below, you are ready to submit your project.
 Did you create an accurate model of calcium carbonate (CaCO3)? Your model should include the correct number of gumdrops for each element in calcium carbonate, consistent use of colors for elements in calcium carbonate, and the correct number and placement of toothpicks (bonds).
 Did you create an accurate model of calcium oxide (CaO)? Your model should include the correct number of gumdrops for each element in calcium oxide, consistent use of colors for elements in calcium oxide, and the correct number and placement of toothpicks (bonds).
 Did you create an accurate model of carbon dioxide (CO2)? Your model should include the correct number of gumdrops for each element in carbon dioxide, consistent use of colors for elements in carbon dioxide, and the correct number and placement of toothpicks (bonds).
 Did you type one to two paragraphs that describe your models and relate them to the law of conservation of mass? Your document should include the names of the reactants and products in the reaction, the number of molecules that make up the reactants and products, and the type and number of atoms in each molecule of the reactants and products. It should also explain what happens during the chemical reaction and how mass is conserved during the reaction
Student Guide (continued)
Step 7: Revise and submit your project.
a) If you were unable to check off all of the requirements on the checklist, go back and make sure that your project is complete.
b) When you have completed your project, submit your models to your teacher for grading. Ask your teacher where to put your name on your models.
c) Submit your document through the virtual classroom. Be sure that your name is on it.
Step 8: Clean up your work space.
a) Clean up your work space. Return any extra materials to your teacher and throw away any trash.
b) Congratulations! You have completed your project.