Teacher Notes



Teacher Notes
Publication No. 12599
Radioactivity HalfLife SimulationStudent Activity KitMaterials Included In Kit
4sided dice, 20
6sided dice, 50 8sided dice, 20 10sided dice, 20 12sided dice, 20 20sided dice, 20 Plastic coins, 100 Additional Materials Required
Cardboard boxes, 15 (optional)
DisposalNo disposal is necessary. Lab Hints
Teacher Tips
Further ExtensionsSupplmentary Information: Radioactive Decay Series {12599_Discussion_Figure_7}
Correlation to Next Generation Science Standards (NGSS)^{†}Science & Engineering PracticesDeveloping and using modelsPlanning and carrying out investigations Analyzing and interpreting data Using mathematics and computational thinking Obtaining, evaluation, and communicating information Disciplinary Core IdeasMSPS1.A: Structure and Properties of MatterHSPS1.A: Structure and Properties of Matter HSPS1.C: Nuclear Processes Crosscutting ConceptsPatternsEnergy and matter Scale, proportion, and quantity Performance ExpectationsMSPS11: Develop models to describe the atomic composition of simple molecules and extended structures. Answers to Prelab QuestionsStrontium90 is a radioactive isotope with a halflife of 29 years. Assume that 10,000 atoms of Sr90 are generated in a nuclear reaction and then stored.
Sample Data{12599_Data_Table_5}
^{1}The number of dice remaining will equal the number of initial dice for the next round. {12599_Data_Table_6}
^{1}The number of dice remaining will equal the number of initial dice for the next round. Answers to Questions
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Student PagesRadioactivity HalfLife SimulationIntroductionRadioactive decay is a spontaneous and completely random process. There is no way to predict how long it will take a specific atom of a radioactive isotope to disintegrate and produce a new atom. The probability, however, that a specific atom will decay after a certain period of time can be simulated by studying other random processes, such as a coin toss or a "roll of the dice." Concepts
BackgroundRadioactive nuclei disintegrate via different processes and at different rates. The amount of time required for different radioactive nuclei to decompose varies widely, from seconds or minutes for very unstable nuclei to a billion years or more for longlived radioactive nuclei. Polonium218, for example, emits alpha particles and decays very quickly—within minutes. Uranium238 also decays via alphaparticle production, but the decay takes place over billions of years! The relative rate of decay of different radioactive isotopes is most conveniently described by comparing their halflives. The halflife (t½) of a radioactive isotope (called a radioisotope) is the amount of time needed for onehalf of the atoms in a sample to decay. Every radioisotope has a characteristic halflife which is independent of the total number of atoms in the sample. Thus, the halflife of polonium218 is about three minutes while the halflife of uranium238 is more than 4 billion years. Regardless of the total number of atoms in a sample of polonium218, onehalf of the atoms will always “disappear” (decompose to produce other atoms) within three minutes. {12599_Background_Table_1_“Radioactive Decay” of Coins}
A simulated “radioactive decay curve” obtained by graphing the data (see Figure 1) shows that the “halflife” of coins is equal to “one coin toss.” The number of coins remaining in the box decreases by 50% after each coin toss.
{12599_Background_Figure_1_“Radioactive decay” of coins}
Experiment OverviewThe purpose of this activity is to simulate radioactive decay by studying the probability of a random process—rolling dice. The “radioactive decay” of dice will be studied by rolling 10 dice ten times in Round 1 and recording the number of dice that display a specific “decay number,” for example, all dice that read six. (Rolling 10 dice ten times is equivalent to rolling 100 dice once.) The total number of dice that “decayed” (landed on six) during Round 1 will then be counted and subtracted from the total number of dice rolled. This is the number of dice remaining that will be rolled in Round 2. This process will be repeated until no dice remain. The “halflife” of dice will be determined by graphing the number of dice remaining after each round. Materials
Cardboard box (optional)
Dice, multisided, 10 Prelab QuestionsStrontium90 is a radioactive isotope with a halflife of 29 years. Assume that 10,000 atoms of Sr90 are generated in a nuclear reaction and then stored.
Procedure
Student Worksheet PDF 