Parent Decay Daughter Formation Curve Start 100 parents; 0 daughters 1 Half-Life 50 parents; 50 daughters 2 Half-Lives 25 parents; 75 daughters And so on… Total # of Atoms remains same
Radiometric Dating Every radioactive isotope has a unique half-life If you know the original amount of radioactive material, it is possible to determine the age of that sample. Two common isotopes Carbon-14 Has half life of 5,730 years Used to detect up to about 50,000 years old Uranium-238 Half-life = 4.5 billion years. Can detect the really old.
For C-14 dating, the object must have carbon in it. Object must have died recently enough to still have carbon-14 in it There is always the same amount of C-14 in life. When you die, you stop getting this new C-14 Find out how much C-14 you have, find out when something died. For U-238 dating, The object must have uranium in it… you get the idea
Practice If a sample contains an isotope with a half-life of 20,000 years, how old would the sample be if: ½ the original isotope remain? 20,000 years 1/8 the original isotope remain? 60,000 years What percent of the sample would be left if the sample was 40,000 years old? 25% (or ¼) Hint: Always start by figuring out how many half-lives there were.
Worksheet If you finish early there is a game online you can play. Check the SWIFT blog.
Radioactive dating game Linked to my web page, or go to: https://phet.colorado.edu/en/simulation/radioactive- dating-game https://phet.colorado.edu/en/simulation/radioactive- dating-game
WHOT Q Create a question about C-14 dating Think… Either about the conditions needed to do it Or A practice problem.
WHOT: Tuesday 12/9 Turn in: Yesterday’s decay WS, make stack of journals at the back table. Objective: Learn a specific example of how Carbon-14 Dating can be used to solve mysteries. Responsibilities: Vocab: Radioisotope, Carbon Dating
Video https://www.youtube.com/watch?v=YWyi ZtagxX8 https://www.youtube.com/watch?v=YWyi ZtagxX8 Take notes on a sheet of scratch paper. (there will be a writing exercise on Carbon dating after the video. Take notes on the science.. How is carbon dating done?
12/10 WHOT Objective: Use your knowledge of radiation to engineer a radioactivity shield. Responsibilities: Quiz this Friday- review notes. Complete Engineering CER’s. Stay tuned for the WHOT riddle at the end of class…
Radioactivity! Yikes What are the first 3 words that come to mind?
Nuclear Reactions Particle Symbol Gamma Composition Charge Mass (amu) Shielding (what will stop it) Biological Damage
Notes Radioactivity Notes Review Radioactivity Radioactivity is the natural process of atoms falling apart. Radioactivity emits both particles and energy as they transform into more stable atoms. Common units: Becquerel, (equal to 1 decay per second), and the Curie, (equal to 37 billion decays per second), and half life. We cannot change the rate of radioactivity. 3 types of radiation: https://www.youtube.com/watch?v=5oUagoF_viQ https://www.youtube.com/watch?v=5oUagoF_viQ
Engineering problems! You have two friends… We will call them Cledus and Eustace. Use CER and your knack as an engineer to help them out. 1. Cledus finds a chunk of strontium-90, a strong Beta emitter in an old hospital. He got super excited that he would turn into a superhero if he slept with it under his pillow. Engineer a solution to save Cledus’s life. Write in complete sentences. You may include a drawing or blueprints on your assignment. Turn this in by the end of class.
Engineering problems! You have two friends… We will call them Cledus and Eustace. Use CER and your knack as an engineer to help them out. 1. Eustace went into his parents wardrobe and came out… somehow magically… with a plastic box labeled Thorium- 232. You remember from science class that large elements are often alpha particle emitters. Design a shield that Eustace could use to protect himself from his newfound radioactive material. Write in complete sentences. You may include a drawing or blueprints on your assignment. Turn this in by the end of class.
WHOT Q Create a question about how C-14 dating is used. This should be different than yesterday’s question as now you have seen how it is used.
WHOT Riddle: You do not have to copy the riddle… just answer it. You can use Both Tuesday and Wednesday Boxes to answer the riddle. You need to explain each You have three radioactive samples, one alpha emitter, 1 beta emitter, and 1 gamma emitter. If you could throw one away, put one in your pocket, and the put the other in a plastic box; what is the best choice? Be sure to explain why (use scientific knowledge).