University of Virginia
Physics Department

## Nuclear Fission and Nuclear Fusion

A Physical Science Activity

2003 Virginia SOLs

• PS.1
• PS.5

Objectives

 Students will visualize the process of nuclear fusion; visualize the process of nuclear fission.

Motivation for Learning

Driving Question

What is the difference between fission and fusion? Can a simple model help visualize the basic concepts?

Background Information

Nuclear fusion is the combining of light elements into heavier ones. Nuclear fission is the splitting of a heavy element into smaller, lighter elements. In both of these processes energy can be released. This demonstration with soap bubbles is limited as a model for fission or fusion because it illustrates only the overall concept. The elements that are missing from the soap bubble model are the neutrons and the energy released during fission, and the protons and energy released during fusion. A nuclear source of energy in nature is the sun. Stars fuse hydrogen atoms into helium atoms and in this process of fusion release energy in the form of electromagnetic radiation.

### Student Activity

Materials

• 2 mL dish detergent (Joy or Dawn work well)
• 5 mL glycerin
• 6 mL water
• Small plastic tray (approximate capacity of 100 mL, approximately 8 cm in diameter)
• 2 pieces of wire (able to be easily bent), 25 cm in length
• Wood splint

Procedure

1. Use the graduated cylinder to carefully measure 2 mL dish detergent, 5 mL glycerin, and 6 mL water into the tray. Use the wood splint to stir the liquid until it is of a uniform consistency.
2. Make two bubble wands from the wire pieces. Take each piece of wire and form a 3-4 cm circle at the center of the length, twist the two ends together to form the handle (see diagram).
3. Hold one wire frame in each hand. Dip the two circular wire frames in the solution.
4. Gently blow through each wire frame to create a bubble with a diameter a little larger than the frame, and catch the bubble on the frame.
5. Bring the frames and the bubbles together. Let the bubbles press against each other until they form one large bubble. This illustrates the fusion process.
6. Stretch the bubble by pulling the two frames farther apart until the bubble separates into two bubbles, one in each frame. This demonstrates the fission process. When this is done a little faster a small bubble may be released, illustrating the released neutron.

Students with Special Needs

Students unable to blow the proper size bubbles or manipulate the wire frames independently can work with a partner or the class can be divided into groups.

Assessment

1. What is the name of the nuclear reaction where small elements combine to make larger elements?

2. What is the name of the nuclear reaction where a large element splits into smaller elements?