Chemistry!! April 28 & 29, 2014 Ms. Boon

Catalyst Objective: I can investigate radiocarbon dating and graph half-life data. Agenda: Catalyst Video Investigation: Radiocarbon dating Investigation: Radioactive Decay Discuss: What do you think “half-life” means? Have you heard of radiocarbon dating? You will be writing your own lab worksheet today. Take out a piece of paper. Or, open a google document on your iPad. This powerpoint is called Radioactive Decay 1.

Radiocarbon dating Video: http://www.youtube.com/watch?v=ErgdpG_N9vQ Video Focus Questions: What are the three natural carbon isotopes and which is radioactive? What material did the scientists start with? What material was sent to the accelerator for dating? How does the accelerator separate the different carbon isotopes? Carbon 12, 13, and 14. C-14 is radioactive. As soon as an organism dies, it does not take in any new carbon and the C-14 begins to decay. Radiocarbon dating compares the amount of C-14 left in the sample versus the amount that occurs normally in a current living organism. They are testing a mummy – specifically, some of the fibers used to dress the mummy They processed the fiber through several high temperature combustions and chemical reactions to end up with graphite. Graphite is a carbon allotrope – it is only made of carbon. The accelerator speeds up the atoms extremely fast with high voltage and a vacuum. It sends them flying around a corner and the heavier C-14 move to the outside while the lighter isotopes move to the inside. The difference in atomic weight is what makes them separate.

Introduction Investigation: Half-Lives and Pennies In this activity, you will work in a group to investigate the idea of radioactive decay. Nuclei with a high proportion of neutrons to protons are generally unstable and undergo radioactive decay. In other words, the unstable nuclei changes to a more stable nuclei of a different element. This decay happens at a constant rate. The time it takes for half of the particles in a sample to decay is called a half-life. The example shows carbon 14 decaying by beta decay into nitrogen 14. It went from 6P + 8N to 7P + 7N.

Materials Procedure Investigation: Half-Lives and Pennies Lined paper Graph paper Plastic cup 80 pennies Textbook Pre-Lab Tasks: Title your paper “Half-Lives and Pennies” Part 1: Copy the definitions of radioactivity, nuclide, and half-life Part 2: Investigation Follow the procedure on textbook pp. 641

Procedure Investigation: Half-Lives and Pennies Part 2: Investigation Follow the procedure on textbook pp. 641 Part 3: Analysis What does your graph look like? Compare your graph to the graph on p. 661. How is it similar or different? Look at Table 2 at the top of p. 659. List the three isotopes with the longest half-lives. Determine how many neutrons and protons these nuclei have before they decay. (Use a periodic table.) Challenge: Read p.658-660 and try practice 1-3 on p. 660.

Part 3: Analysis What does your graph look like? Compare your graph to the graph on p. 661. How is it similar or different? They have the same shape because half goes away each trial. Look at Table 2 at the top of p. 659. List the three isotopes with the longest half-lives. Determine how many neutrons and protons these nuclei have before they decay. (Use a periodic table.) Potassium -40, uranium-235, and uranium 238

Research Choice #1: Energy Sources overview Open up the document titled “The Energy Source Buffet” posted on the www.ouchihs.org website. Gather information on your Energy Project graphic organizers. Nuclear Vocabulary Practice: http://quizlet.com/40587747/nuclear-chemistry-flash-cards/

Research Choice #2: Nuclear Energy Research http://blnds.co/1nBsMBr Beginning with the resources posted on this blendspace, gather information both for and against the use of nuclear energy as part of your energy proposal. Nuclear Vocabulary Practice: http://quizlet.com/40587747/nuclear-chemistry-flash-cards/

sample persuasive essay paragraph Sample topic: Should more students take AP courses? All Ouchi high school students should take at least two AP courses during high school. Research has shown that students who take AP courses and the AP test have more success in college. (Washington Post, 2014.) Students who take AP courses, even if they fail the AP test, are more likely to graduate college than students who take no AP courses. (Washington Post.) Training students to be college-ready is part of Ouchi’s mission. Therefore, all Ouchi students should take AP courses so that all students are better prepared for college. Topic Sentence: States the argument. Highlight the topic sentence – sets out the position. Facts/Evidence is next. Next is a reason that explains why the facts support the position – notice that this is obvious but it is still written down. Finally, conclusion that links the reason to the position. Evidence with citation to source. Reason/Analysis: Why the evidence supports argument. Conclusion Sentence: States the argument.

Computer Simulation Radio Carbon Dating Game!

Exit Slip(s) Nuclear #1 (absent last Thurs/Fri & P2): http://tinyurl.com/boonchem22 Nuclear #2: All students http://tinyurl.com/boonchem23 Use your notes. Work silently. Homework: Complete your nuclear power research. https://docs.google.com/forms/d/1ZuFJEgIF948RTLyfLmb_L1hIuUOj8jyrVPnoQd1ZgNo/viewform?usp=send_form https://docs.google.com/forms/d/1J0HAwEUnEhWpFj75QgOUDuDaesvErvwUWvsncB9laHw/viewform?usp=send_form