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Themes: Stability and Change Conservation of Energy and Matter.

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Presentation on theme: "Themes: Stability and Change Conservation of Energy and Matter."— Presentation transcript:

1 Themes: Stability and Change Conservation of Energy and Matter

2 When a radioactive nucleus spontaneously decomposes.

3  In a nuclear equation both the atomic number and the mass number must be conserved.  How is that shown below??

4 AlphaProduces Helium Nucleus Atomic Mass: Decrease by 4 Atomic #: Decrease by 2 BetaProduces An electron Atomic mass: Same Atomic#: increase by 1 GammaProduces Energy Usually accompanies another type of decay Atomic mass and atomic number remain the same.

5 PositronProduces Like a positron with a + charge Atomic Mass: Same Atomic #: Decrease by 1 Electron Capture Inner electrons are captured by the nucleus. Atomic Mass: Same Atomic number: Decrease by 1

6 Nuclear Bombardment A particle is shot into the nucleus: Eg. Alpha particle or a neutron See Example below: Mass: Will increase Atomic #: Will usually change

7

8  Geiger Counter—Radiation produces ionizing energy that knocks off electrons from argon. This causes an electric current which is detected.  Fiesta Ware Demonstration on youtube. http://www.youtube.com/ watch?v=FKn9zJuyfWQ

9 TypePenetrationDamaging Effects AlphaBlocked by skinIonizing substances in the body causing damage BetaPenetrates 1 inch into skin, can be blocked by Aluminum foil Least damaging GammaDeep penetration. Blocked by lead Damaging because this is a very high energy form of electromagnetic radiation. Eg. Most commonly used to kill cancer cells

10  Positive Uses  Detection on imaging machines  “Killing” cells in tumors that can’t be  Negative Affects  High exposure—damaging to cells (eg. Hiroshima)  Long term low exposure—  Mutation to DNA leading to cancer  Mutation to DNA in eggs/sperm

11  Time required for half of the original same of nuclei to decay. Carbon-14 half-life5730 years Uranium-238 half-life4.5 billion years Iodine-131 half-life8.1 days

12  What type of function is this?

13  Use howstuffworks.com to investigate nuclear fission and fusion.  Create a Venn Diagram in your notes to compare and contrast the two processes

14  Using Pennies to model radioactive decay.  Practice graphing and lab notebook skills!


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