1. Growth and Decay

2. The Half-Life Time of a Radioactive Elements

3. Therefore; Half-life for a radioactive material is the time requires for the material to decay in half. Half-life for some of the radioactive materials: Polonium-210 : 210 days carbon-14 : 5700 uranium : 4.5 billion years Half-life =

4. Cave painting at Lascaux, France Archeologists were able to determine the approximate time at when these paintings were created by using carbon-14 which has a half-life about 5700 years.

5. Example1 (Class Work) The half-life of phosphorus-32 is about 14 days. There are 6.6 grams present initially. (a) Express the amount of phosphorous-32 remaining as a function of time t. (b) When will there be 1 gram remaining?

7. Example2 (Home Work) Carbon 14. Half-life of carbon-14 is 5700 years. Find the age of a sample in which 10% of the radioactive material presented initially have decayed.