1. 25.4 – Nuclear Reactions
VIDEO CLIP

2. Objectives
Explain nuclear fission and how it can begin a chain reaction.
Discuss how nuclear fusion occurs in the sun.
Describe how radiotracers can be used to diagnose medical problems.
Discuss how nuclear reactions can help treat cancer.

3. Mass & Energy
A small amount of mass can be converted into an enormous amount of energy

4. Nuclear Fission
The process of splitting a nucleus into two nuclei with smaller masses
Releases a large amount of energy

5. Chain Reaction An ongoing series of fission reactions
Critical mass = the amount of fissionable material required to continue a reaction at a constant rate

6. Nuclear Fusion
The process by which two nuclei with low masses are combined to form one nucleus of larger mass

7. Can happen only when nuclei are moving fast enough to get close to each other
Temperatures in stars (millions of Celsius) are high enough for fusion to occur

8. Nuclear Reactions Medical uses
Radioisotopes are used as radiotracers to find or keep track of molecules in an organism.
Cancer cells can be killed with carefully measured doses of radiation

9. Add to notes Radiotracers
Radioisotopes used to find or trace molecules in an organism
Scientists use them to follow a particular molecule as it goes through your body or to study how a particular organ functions
Examples: carbon-11, iodine-131, sodium-24

10. In-Class Assignment/Homework
25.4 WKT