Fusion vs Fission

Fission/Fusion Better Lesson credit R.Meisner w/add-ins RMohler nuclear fusion vs nuclear fission How can you explain these terms?

Nuclear Reactions - Reactions involving changes in the nucleus of atoms - Nuclear reactions release MUCH MORE energy then chemical reactions (which deal with electrons only)

E=mc2 Einstein’s famous equation relates mass and energy. Energy and mass are interchangeable. E=Energy, m=mass, c=speed of light (3x108m/s) When a high-energy gamma ray is given off, the mass of the nucleus drops a measurable value. Similarly, we can calculate how much energy will be given off in particular nuclear reactions. We use the formula ΔE= Δmc2 to build new, artificial elements in supercolliders (particle accelerators.)

Two major types of nuclear reactions: Fission Fusion

Nuclear Fission Nuclear fission = splitting of large, unstable atoms Releases large amounts of energy Uncontrolled, nuclear fission proceeds to completion with great speed.

Nuclear Fission Used in nuclear weapons and power plants (U-235) In a nuclear weapon, two half-spheres of fissionable material are compressed together with conventional explosives, creating the critical mass. In order to harness nuclear fission to create useable electricity, the process is slowed down with control rods…

Fission Reactor Power Plants (do not need to copy this In each reactor, heat is generated when high-energy neutrons slow down in collisions with the moderator. Pressurized Steam Reactor:Steam is produced and drives turbines, creating electricity. Reactor fuel must be fissionable, usually weapons-grade uranium or plutonium. Moderators become highly radioactivity (dirty).

Nuclear Fusion Nuclear Fusion: Joining of smaller nuclei to form larger nuclei. Releases far more energy than nuclear fission (3-4 xs more).

Nuclear Fusion The sun’s (stars) energy comes from the fusion of hydrogen atoms into helium atoms. The hydrogen bomb is a fusion weapon. Extensive research is being carried out to find ways of creating and harnessing nuclear fusion for industrial power production. Unlike fission, fusion reactions can be easily controlled, by controlling the fuel flow.

Modeling Fusion reactions (like what happens in the sun). marshmallow= hydrogen nucleus (1 proton) pipe cleaner/spaghetti = gamma ray What element does one marshmallow represent? Take two marshmallows and fuse together using the energy of your hands (like the sun with high temperature and pressure). What element have you produced?

What’s happening… At the same time that you fuse the atoms together they release energy as a gamma ray. Take a piece of pipe-cleaner/spaghetti and put on your table. This is energy of the gamma ray. Make two more helium atoms (with four more marshmallows, making sure to release gamma rays) Now smash together your three helium nuclei. In what is called the “triple-alpha process”. What is this called (fission or fusion)? What new element did you produce? Eat your final atom