Objective: Determine what happens during alpha decay and see how half-life relates to this form of radiation Procedure

Alpha Decay Lab

Name:_________________________________

Date:_____________________ Period:_______


Objective:
Determine what happens during alpha decay and see how half-life relates to this form of radiation
Procedure:

Go to the Alpha Decay simulation linked below and following the instructions that follow.

http://phet.colorado.edu/simulations/sims.php?sim=Alpha_Decay
You will begin by studying Alpha Decay for a single Polonium-211 atom and then study nuclear half-life for a series of Polonium-211 atoms.
Alpha Decay

1. 
   What does the alpha particle consist of? Click on “Single Atom” and then the play icon at the bottom of the screen to start the simulation. Watch the Polonium atom in the center of the screen. Pause right after the Polonium atom ejects something. This is the alpha particle. Hit “Reset Nucleus” to watch again if you need.
   

2. 
   Why does the mass number change from 211 to 207 after the decay?
   

3. 
   Are mass and charge conserved during the nuclear reaction? How do you know?
   

4. 
   Write the nuclear reaction that occurs.
   

5. 
   Record observations of the nuclear energy and alpha particle energy before and after the reaction by watching the display at the bottom. Reset the simulation if needed to watch the reaction.
   

6. 
   Why does this change in nuclear energy occur? Where does the nuclear energy go?
   

Half-life
You will now study radioactive decay as a function of time. Click “Multiple Atoms” and then “Add 10” at the bottom of the screen to add 10 Polonium atoms to the simulation. They’ll start to decay right away but you’ll reset all nuclei once you are ready to proceed.

1. 
   Once you’re ready, you’ll pause the simulation every 0.5 seconds (one half-life) and record the number of Polonium atoms present.
   

Time (s)	# of Polonium Atoms
0
0.5
1.0
1.5
2.0
2.5
3.0

2. 
   Sketch a graph of the # of Polonium atoms versus time.
   

3. 
   Add a trendline to your graph and identify what type of mathematical function this represents.
   

4. 
   Each half-life results, on average, with half of the samples decaying. How closely did your sample decay in accordance with this relationship? Justify your response.