#2037. Chemical bonding

Science, level: Elementary
Posted Tue Nov 28 07:00:01 PST 2000 by Jenifer Jacobs (JJacobs98@hotmail.com).
Indiana University of Pennsylvania, Indiana, USA
Materials Required: Diluted polyvinly alcohol, borax, cups, popsicle sticks, paper towels,plastic bags
Activity Time: 45 minutes
Concepts Taught: To gain knowledge on the concept of chemical bonding.

I. HEADING
Jenifer Jacobs
Science- 20 students
3rd grade- 45 minutes
November 13, 2000

II. OBJECTIVES

1. TLW expand their knowledge on the process of chemical bonding.
2. TLW interact and participate with the class.
3. TLW combine various chemicals to create a blob.

III. MATERIALS

· Diluted polyvinyl alcohol
· Borax
· plastic cups
· Popsicle sticks
· paper towels
· plastic bags

IV. PROCEDURES

A. Introduction
TTW show the students an example of a blob that was previously made. The students will have an opportunity to pass the blob around the class examining its texture and make-up. TTW ask the students to discuss their thoughts and ideas on the possible components in the blob and how they think it was formed. After the discussion, TTW introduce the term chemical bonding, which is the force of attraction that holds two atoms together. TTW explain that the blob was formed through a chemical bond, and that they will have a chance to make their own blob.
B. Activity
TTW give each student a cup with diluted polyvinyl alcohol in it. TTW ask for five volunteers to stand in a straight-line beside one another. TTW explain that each of these students represents a mer. A mer means one unit. TTW instruct the five students to join hands. Now they have formed a polymer, which means many units. TTW lead the chain around the room pointing out its flexibility and mobility. Five more volunteers will form a chain and walk around the room just like the first chain is doing. TTW explain that the solution that is in their cups contain many polymers like the two that we have formed, moving around freely with lots of water between them. TTW explain that the next chemical that will be added to their cups will link the polymer chains together, and is called a crosslinker. The two chains will form parallel lines close together. TTW act as the crosslinker and hold on to the wrists of each polymer as they try to move around as they did earlier. TTW point out that although the polymer chains can move some, they are not as flexible as they were before. The volunteers will take their seats. TTW add the last chemical, borax, to the cups. TTW instruct the students to vigorously stir the solution in their cups with their popsicle stick. TTW will explain that as the mixture gels, it is acting as a crosslinking agent. It is binding polymers together so they can not move about as freely. Once the gel has formed, the students will be instructed to remove the gel from their cups and knead it to make the consistency stronger.
C. Conclusion
The students will throw away their popsicle sticks and cups. TTW pass out plastic bags for the students to put their blobs in. TTW review the steps of their experiment and answer any questions the students might have.

V. EVALUATION

TLW be evaluated on their participation during the experiment and the end result of their blob.