Summary

In this activity, students match puzzle pieces to create neutral ionic compounds. They use electron dot diagrams to show the formation of the compounds. Finally, they will name the ionic compounds.

Grade Level

High and Middle School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

• HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
• Science and Engineering Practices:
  • Developing and using models
  • Using mathematics and computational thinking

Objectives

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

• Understand that ionic compounds must be neutral .
• Use electron dot diagrams to show how ionic compounds form.
• Write chemical formulas with correct subscripts.
• Name ionic compounds.

Chemistry Topics

This activity supports students’ understanding of

• Ionic Bonding
• Polyatomic ions
• Naming ionic compounds
• Electron dot structures

Time

Teacher Preparation: 1 hour (the first time)

Lesson: 50 minutes

Materials

• Puzzle pieces (cut out in advance)
• Student worksheets for each student or group
• Periodic table

Teacher Notes

• Before this activity can be done the first time, the teacher will need to cut out and bag up all the pieces (they can be laminated, if you want). Alternately, have students cut out the puzzle pieces themselves and provide plastic bags for students to store them. 
• The puzzle pieces can be copied for as many pairs/groups as there will be. I have found that it is helpful to number the pieces and put them in numbered bags so that you can easily put a dropped piece where it goes (or make the pieces on different colors of paper).
• This activity can help students who take longer to understand writing chemical formulas. Using this activity provides the option to use the puzzle pieces for supporting their understanding of how to properly write formulas.
• Teachers should be familiar with the rules for naming and formula writing for ionic compounds.
• I have found it helpful to introduce the activity, have students work in pairs and then debrief as a class and/or have students complete an exit slip at the end of the class time.
• Walking around to monitor student progress and check for understanding is helpful in guiding students through the questions.
• Students usually pause when faced with a combination such as Fe⁺² and P^-3. Their first reaction will not be to use another positive or negative puzzle piece. Modeling the first one for them (if they get stuck) can help them get going when the puzzle pieces don’t match up perfectly.
• Students may not understand that the name of an anion should end in “-ide.” Remind them to change the ending.
• For higher levels you could include more names and formulas. For lower levels you could reduce the size of the so students can focus on the inquiry.