Themes: Stability and Change Conservation of Energy and Matter

 What types of isotopes are unstable?  Unstable isotopes have larger differences between number of protons and neutrons.  Look at your periodic table…what happens as the atomic # gets higher?

When a radioactive nucleus spontaneously decomposes.

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

 The types of nuclear reactions we will go over are as follows.  The examples are on the powerpoint for your review, but we will do examples on the board in class:  Alpha  Beta  Gamma  Positron Emission  Electron capture  Nuclear bombardment

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.

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

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

 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. watch?v=FKn9zJuyfWQ

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

 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

 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

 What type of function is this?

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

 Case study will identify the use of isotopes in medicine.  Model will use pennies to represent radioactive decay.  Practice graphing and lab notebook skills!