Half Life - A half life is the amount of time that it takes for half of a given sample to decay into something else Example: Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. After 10 minutes, how much will be left?

Half Life -Half lives can be used to date different materials -By knowing the ratio of the isotopes you have, you can determine the age of your sample

Half Life -Carbon-14 has a half life on 5730 years -A sample that contains 100 g of C-14 when it should normally have 200 g is 5730 years old - A sample that contains 50 g of C-14 when it should normally have 200 g is 11460 years old

Half Life Practice 1. Iodine-131 is used to destroy thyroid tissue in the treatment of an overactive thyroid. The half-life of iodine-131 is 8 days. If a hospital receives a shipment of 200 g of iodine-131, how much I-131 would remain after 32 days? 2. Technetium-99 is used for brain scans. If a laboratory receives a shipment of 200 g of this isotope and after 24 hours only 12.5 g of this isotope remain, what is the half-life of technetium-99?