Half - Life

Rubric for Pros/Cons of Nuclear Power Presentation Nuclear Unit Syllabus The final rubric for presentations contains the expectations for the end product – what areas will be included and a scoring range for each area Rubric for Pros/Cons of Nuclear Power Presentation Needs Improvement Minimal Expectation Exceeds Expectations Points 1 2 3 Time Less than 5 min 5 min › 5 min but ‹ 10 min Research No outside research 1 additional source 2 additional sources Material No equations Equations from lecture Equations from lecture and outside sources Pros/Cons Polarized opinions only Pros/Cons but not balanced Balanced with final viewpoint and one additional question.

Rubric for Team Debates Nuclear Unit Syllabus The final rubric for debates contains the expectations for the end product – what areas will be included and a scoring range for each area Rubric for Team Debates Needs Improvement Minimal Expectation Exceeds Expectations Points 1 2 3 Valid /convincing mutual arguments Skeptical response from listeners Makes valid points Makes valid and convincing points, convinced others Research No research 1 source worked into comments 2 or more sources worked into comments Presenting /Listening Distracting Good presentation, poor listening Presented well and listened to other team Debate/ Counter Polarized opinions /arguments only Good arguments but not able to counter other team Good balanced arguments with well thought out counter to other team

Presentation and Debate Teams Tyler/Patrick – Con side in debate Aaron/Jason – Pro side in debate Danielle/Tim – Pro side in debate Jessica/Josh – Con side in debate Nick/Raquel – Con side in debate Kristin/Cortney – Pro side in debate Sean B./Zack – Pro side in debate Cameron/Sean P. – Con side in debate

GLE Describe radioactivity Work with real life examples of half-life to discuss problem with nuclear waste storage Define half-life and come up with half-life equation Objective Student will use half-life activity to come up with an equation for half-life, use half-life information to determine the amount of a radioisotope remaining at a given time, and discuss the consequences of storing nuclear waste from a half-life point of view.

Radioactivity In nuclear reactions, the nuclei of unstable isotopes, called radioisotopes, gain stability by undergoing changes accompanied by the emission of large amounts of energy. The process by which materials give off such energy, in the form of waves (rays), is called radioactivity. Waves and particles emitted are called radiation.

Half-Life Activity Each table pick up a bag of popcorn, worksheet packet, and 3X5 card. Follow the instructions on the first page of the worksheet package. Be prepared to discuss your findings with the rest of the class. As part of those findings each team will come up with their definition for half-life

Half-Life Every radioisotope has a characteristic rate of decay measured by its half-life A half-life is the time required for one-half of the nuclei of a radioisotope sample to decay to products. After one half-life, half of the original radioactive atoms have decayed into atoms of a new element. How many are left after two half-lives? What value is never reached?

Half-Life Equation As a class, come up with a working half-life equation. Activity final = Activity initial (1/2) time passed/half-life

Half-Life Half-lives may be as short as a fraction of a second or as long as billions of years. Many artificially produced radioisotopes have very short half-lives, a feature that is a great advantage in nuclear medicine. The rapidly decaying isotopes do not pose long-term biological radiation hazards to patients.

Radioactive Intermediates When radioisotopes decay, they may decay to another element that is also unstable These elements that are unstable have half-lives of their own. Elements that are unstable and undergo further decay until a stable nucleus configuration is reached are called radioactive intermediates.

Homework Page 851, # 6 and # 10.