Nuclear Fusion Activity

Name:______Period:______

Objective: Use a simple model to demonstrate nuclear fusion and how radiation is generated by stars.

Procedure:

Stars like our sun are composed mainly of hydrogen and helium. Locate these elements on the period table. What is the atomic number for hydrogen? ______For helium? ______Remember that the atomic number of an element tells us how many protons are found in the nucleus of that atom.

Each marshmallow in our model represents one proton. Pick up one marshmallow in each hand. You are now holding two atoms of which element? ______. Note: all atoms in the sun’s core have been stripped of their electrons by the intense heat and pressure, so we are dealing with only the nuclei of the atoms in this model.

Your hands are now the core of a star. Temperatures and pressure are so intense that the atoms in the core are moving incredibly fast. So fast that they can overcome the repulsive force between two positively charged particles and actually crash into each other! Squeeze your hands together to model this collision.

When two hydrogen nuclei collide, the strong nuclear force holds them together. You should now be holding an atom with two protons – AKA ______. This process of fusion releases large amounts of energy, because some of the mass from the hydrogen nuclei is converted to energy (E = mc2). Note: There are actually multiple steps involved in this process. We are modelling a simplified version of what happens. For more a detailed description, follow the links on my webpage.

In older stars, much of their hydrogen has been converted into helium. If the temperature gets high enough, the cores of these stars can continue fusion through the triple-alpha process. To model this, take two of your helium nuclei (also called alpha particles) and smash them together. This forms a very unstable beryllium atom. If a third helium nucleus hits it before it disintegrates, a new element with six protons is formed. Smash all three of your helium nuclei together. What element have you created? ______

Carl Sagan said, “We are made of STAR STUFF”. All organic molecules on Earth contain carbon. You may now eat your marshmallows as you ponder that quote and complete the following analysis questions.

Analysis Questions:

1)What is the name of the process by which stars generate energy?

2)Atoms of which element arefound at the beginning of this process?

3)By the end of this activity, atoms of which twoelements have been created?

4)What is released as a result of this process?

5)Explain how the process of nuclear fusion is connected to Einstein’s equation E=mc2

E= energy m = mass c = the speed of light (a constant)