Friday Dec 12 Objective: Calculate the half-life of radioactive materials. Checkpoint: What is the half-life of a radioactive sample if it takes 10 years for a 100 gram sample to decay to 50 grams? Homework: – Study guide (due Tuesday beginning of class)

Half-Life The time it takes for half of a radioactive sample to decay. 100 g 50 g 10 years

Underground repository for used fuel (1650 ft underground)

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of Iodine-131 is 8 days.

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of Iodine-131 is 8 days. 8 days

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of Iodine-131 is 8 days. 16 days

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of Iodine-131 is 8 days. 24 days

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of Iodine-131 is 8 days. 32 days

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of Iodine-131 is 8 days. 40 days

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of Iodine-131 is 8 days. 48 days

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of radioactive Uranium-238 is 4.46 billion years.

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of radioactive Uranium-238 is 4.46 billion years billion years

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of radioactive Uranium-238 is 4.46 billion years billion years

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of radioactive Uranium-238 is 4.46 billion years billion years

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of radioactive Uranium-238 is 4.46 billion years billion years

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of radioactive Uranium-238 is 4.46 billion years billion years

Half-Life The time it takes for half of a radioactive sample to decay. The half-life of radioactive Uranium-238 is 4.46 billion years billion years

2) How much of a 100 grams of a radioactive sample is left after 50 years if its half life is 10 years? 100 g 50 g 1 half life (10 years) 25 g 2 half lives (20 years) 12.5 g 3 half lives (30 years) 6.25 g 4 half lives (40 years) grams 5 half lives (50 years)

5) What is the half-life of a radioactive sample if it takes 200 years for a 100 gram sample to decay to 25 grams? 100 g 50 g 25 g 1 half life 2 half lives 200 years Half-life = 200 / 2 = 100 years

7) A radioactive sample has a half-life of 30 years. How many years must pass to reduce a 50 mg sample to 6.25 mg? 50 g 25 g 1 half life (30 years) 12.5 g 2 half lives (60 years) 6.25 g 3 half lives (90 years)

Radioactive Decay Lab

Trial # # isotopes