Respond to the following: “Don’t watch the clock; do what it does. Keep going.” -Sam Levenson After the bell (2 min) In your seat: With pen/pencil With Notebook With Handouts Silent and ready for Do Now Homework on your desk When the bell rings DO NOW

NUCLEAR CHEMISTRY: HALF-LIFE Objective: Describe the decay of isotopes through half-life

 Do Now (5 min)  Upcoming: Unit 2 Test  Warm Up (5 min)  Notes: Half - Life(30 min)  Activity: Half-Life of a penny (10 min)  Independent Practice: (20 min)  Exit Slip (5 min)  Closeout (2 min) AGENDA HONORS/ PRE-IB

GUIDING QUESTION Why can’t you just clean up after a nuclear disaster?

Draw the Bohr model for Neon An ion occurs when an atom gains or loses electrons to form a bond. Draw the Bohr model for an atom of Cl that gains an electron when it bonds with Na. What is the resulting charge? What? C – Level 1-2, amongst group H – Raise hand A – Discuss prompt M – None P –Recording responses on left page, discussing with group How? WARM –UP:

ISOTOPE What is an isotope? Isotope : any forms of an element that have the same number of protons, but a different number of neutrons. In other words, it will be the same element, with a different atomic mass

ISOTOPE EXAMPLES

HALF - LIFE Definition: The Amount of time it takes for one-half of a sample of atoms to decay. Half-Life Decay of a Radioactive Isotope Half-Life Isotope remaining 0100% 150% 225% % 46.25% 53.12%

LOOKS LIKE THIS… March Madness Bracket

HOW MUCH WILL REMAIN Barium-122 has a half-life of 2 minutes. If you receive 80 g of Barium-122, how much will be remaining after 10 minutes? 1.Set up a 3 column table 2.Label the columns: half-life, time, amount 3.Fill in the information you are given (starting with time 0 and half- life 0, for original amount only) 4.Work forwards or backwards to reach the answer Half-LifeTimeAmount

YOU DO How much of a g sample of 198 Au is left after 8.1days, if its half-life is 2.70 days? 1.Set up a 3 column table 2.Label the columns: half-life, time, amount 3.Fill in the information you are given (starting with time 0 and half- life 0, for original amount only) 4.Work forwards or backwards to reach the answer

HOW MUCH TO BEGIN WITH There are 5 g of 131 I left after days. How many grams were in the original sample if its half-life is 8.07 days? 1.Set up a 3 column table 2.Label the columns: half-life, time, amount 3.Fill in the information you are given (starting with time 0 and half- life 0, for original amount only) 4.Work forwards or backwards to reach the answer Half-LifeTimeAmount ?40.35 days5g

YOU DO If the passing of five half-lives leaves 25.0 mg of a strontium-90 sample, how much strontium-90 was originally present? 1.Set up a 3 column table 2.Label the columns: half-life, time, amount 3.Fill in the information you are given (starting with time 0 and half- life 0, for original amount only) 4.Work forwards or backwards to reach the answer Half-LifeTimeAmount

LENGTH OF HALF - LIFE If 100g of Au-198 decays to 6.25 g in 10.8 days, what is the half-life of Au-198? Total time elapsed Number of half lives gone by Length of a single Half-Life Half-LifeTimeAmount g 1 ? 50 2 ? 25 3 ? days 6.25g

YOU DO A 50.0 g sample of 16 N decays to 12.5 g in 14.4 seconds. How long is its half-life? Half-LifeTimeAmount Total time elapsed Number of half lives gone by Length of a single Half-Life

Instructions are in your packet Using 50 coins, not 100 Using Tupperware instead of Ziploc bags What? C – Level 1-2, on-task discussion H – Raise hand A – Answering questions as a small group at lab M – None P – Recoding answers on worksheet, head up, reading and thinking through all questions, discussing with group How? MINI – LAB: HALF-LIFE

10 minutes silently  Discuss for 5 minutes in small groups  Verify & Review as class What? C – None H – Raise hand A – Answering questions to determine # of subatomic particles M – None P – Recoding answers on worksheet, head up, reading and thinking through all questions. How? ACTIVITY: INDEPENDENT PRACTICE

If you finish early, summarize what you learned at the bottom of your notes OR answer today’s guiding question What? (5 min) C – No talking H – Raise hand A – Taking exit slip M – In seat P – Completing exit slip without notes and turning in How? EXIT SLIP

CLOSING What are 3 key takeaways from today and yesterday? Complete the 3 stretch questions Be ready to discuss Fusion, Fission and Decay next class Forgetting to stretch is a bear.