25.4 – Nuclear Reactions VIDEO CLIP

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.

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

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

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

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

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

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

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

In-Class Assignment/Homework 25.4 WKT