LAB in Molecular Formula. Last updated June 5, 2017.
In this lab, students build Lego models of ionic and covalent compounds.
By the end of this lesson, students should be able to
- build models of different compounds.
- examine ratios of atoms in the compounds.
- compare and contrast the basic structure of ionic and molecular compounds.
This lesson supports students’ understanding of
- Ionic bonding
- Covalent bonding
Teacher Preparation: 10-15 minutes
Lesson: 30 minutes
For each group:
- Legos (up to you whether students define what Legos represent or you decide)
- Student activity sheet
There are no special safety considerations for this activity.
- Make sure that each group has enough of the same type of Lego to build each of the models.
- You can determine ahead of time which Lego represents each element, or allow each group to decide for themselves.
- See PowerPoint for the three rules that go in the “Notes” section on the Student Activity Sheet. They are: 1) Opposite charges attract, like charges repel. 2) Ions don’t lose their charge in an ionic compound (they balance their charges to make a neutral compound). 3) Molecules never have a charge.
For the Student
Write down the three rules discussed in class about compounds.
Build models of various chemical compounds.
Examine ratios of atoms in the compounds.
Compare and contrast the basic structure of ionic and molecular compounds.
For each compound given
- Determine if the bonding atoms (in the chart below) are metal-nonmetal or nonmetal-nonmetal combinations.
- Based on your answer to #1, determine the probable bond type.
- Build appropriate models using Legos (minimum of three formula units for each compound).
- Make an appropriate sketch of your model(s).
- Have your teacher check each model before you take them apart (you should continue to work ahead, don't stop and wait).
Metal-Nonmetal or Nonmetal-Nonmetal
Ionic or Molecular
Sketch of Model(s)
- How did you determine whether the compound was ionic or molecular?
- What was the main difference between your models of ionic and molecular compounds?
- If you have 10 sodium atoms and 10 chlorine atoms, how many units of NaCl could you make? _____ Draw them.
- If you have 10 sodium atoms and 10 chlorine atoms, how many units of Na2Cl2 could you make? _____ Draw them.
- Do your answers to 3 and 4 differ? Why?
- If you had 12 carbon atoms and 12 hydrogen atoms, how many units of C2H2 could you make? _____ Draw them.
- If you had 12 carbon atoms and 12 hydrogen atoms, how many units of C6H6 could you make? _____ Draw them.
- Do your answers to 6 and 7 differ? Why?
- Basically, all ionic compounds are solids. Explain.