to write a chemical formula and name of an ionic compound compounds react to
... 2) All students create an answer sheet that they will fill out during the activity.
Donna Donovan Best Teaching Practices: Simulation, Inquiry and Cooperative Learning Activity Topics: Ionic Compounds and Double Replacement Reactions Overview: Students engage in activities that lead to an understanding of how ions come together to form compounds to write a chemical formula and name of an ionic compound compounds react to form new substances. Activity 1: Compound Creation 1) Prior to this activity, the teacher constructs ion hats. Each hat has the name and symbol of one ion. ( a suggested list of ions is in step #3)
2) All students create an answer sheet that they will fill out during the activity. This answer sheet has two headings as shown below. A sample answer is given. Compound’s Chemical Formula
Compound’s Name
1) CaCl2
calcium
chloride
2) __________
_________ _________
3) Students are placed into one of 10 different groups. Each group consists of either 2 or 3 students. All group members will wear an ion hat. Here is a list showing how to create the groups and what ion hats they’d wear. Modify the number of groups according to how many students you have. For example you could merge groups 1 & 2 into one group of 5 students. Try to end up with an even number of groups. You could also expand your ion list to include polyatomic ions and those requiring a Roman numeral in their name. Group #1 three members: hats Na+1, Na+1, Na+1 Group #2 two members: hats Al+3, Al+3 Group #3 three members: hats Ca+2, Ca+2, Ca+2, Group #4 three members: hats K+1, K+1, K+1 Group #5 three members: hats Ba+2, Ba+2, Ba+2 Group #6 three members: hats Cl-1, Cl-1, Cl-1 Group #7 two members: hats P-3, P-3 Group #8 three members: hats S-2, S-2, S-2, Group #9 three members: hats Br-1, Br-1, Br-1 Group #10 three members: hats O-2, O-2, O-2
4) Create 5 different “ compound formation locations” throughout the classroom. I use the 4 corners and center of the room with a circle marked off on the floor.
5) When the whistle blows, all members of the group must go to one of the “compound formation locations” throughout the room. Only 2 different groups can be together at one location at the same time, and these two groups must contain oppositely charged ions. An example is shown below Group #4 K+1, K+1, K+1 and Group #7 P-3, P-3
6) The two groups at each compound formation location have 3 minutes to interact and create an ionic compound by linking together oppositely charged ions in the smallest whole number ratio so that the sum of the charges equals zero. They are not formally instructed how many positive and negative ions to put together, they must reason it out. Each group member then prints the chemical formula and name of the compound they create on their answer sheet. When the whistle blows groups head to different locations and pair up with a different group to create a different compound. Not all group members will be used for each combination of groups. It’s up to the students to decide how many ions are involved to make the sum of all charges equal zero. Here are some photos of students creating compounds and the answer they placed on their answer sheet. Compound’s Chemical Formula CaS
Compound’s Name calcium sulfide
Compound’s Chemical Formula CaCl2
Compound’s Name calcium chloride
Compound’s Chemical Formula Al2S3
Compound’s Name aluminum sulfide
Compound’s Chemical Formula Na2S
Compound’s Name sodium sulfide
7) Assessment: The first assessment is the answer sheet turned in for this activity. After doing this activity, give students more practice naming compounds and writing their chemical formula using teacher generated handouts and book problems. Then you could either give the students a written quiz or have them come to the board to answer the questions. For half the questions, you provide the name of the compound and the student prints the formula. For the other half, you provide the formula and they print the compound’s name. This can be turned into a friendly competition by pitting one group against another and keeping score.
Activity 2: Double Replacement Reactions Once students gain an understanding of how ions combine to create compounds, you can use the hats to lead them to an understanding of double replacement reactions. 1) Divide students into groups and give each group a specific reaction to act out in front of the class and represent with a balanced chemical equation they print on the board. Do not tell them what products form or what coefficients appear in the equation. Just instruct them to create the reactants, break apart, and create new products with ALL the ions.
Example : sodium sulfide reacting with calcium chloride REACTANTS
Na2S
PRODUCTS
+
CaCl2 2 NaCl + CaS
2) Assessment: The group is given a grade based upon their ability to accurately act out the reaction and represent it with a balanced chemical equation. THE END
