Ios 7 Article

8.01 Lab Report
FLVS

The purpose of this hands-on lab is to model the concept of half-life using a sample to represent radioactive atoms. Materials 200 M&M® candies, pennies, or other small candy/item with two distinct sides shoe box or other small box with a lid.
Procedure
1. Place 200 candies in the shoe box, lettered sides up. The candies will stand for atoms of a hypothetical radioactive element.

2. Cover the box and shake it vigorously for three seconds. This is one time interval.

3. Remove the lid and take out any candies (atoms) that have that are now showing lettered sides down. These candies represent the atoms that decayed during the time interval. Count and record in a data table the number of decayed atoms and the number of remaining, not decayed, atoms.

4. Continue repeating steps two and three until all atoms have decayed or you have reached 30 seconds on the data table.

5. Repeat the entire experiment (steps 1–4) a second time and record all data. Data and Observations

Create and complete a data table, like the one below, for each trial. Time (seconds)
Radioactive atoms remaining (not decayed)
Atoms decayed
0
200
0
3
178
22
6
165
13
9
156
9
12
141
15
15
110
31
18
103
7
21
76
27
24
60
16
27
56
4
30
45
11
Calculations
Trial 2;
Time (seconds)
Radioactive atoms remaining (not decayed)
Atoms decayed
0
200
0
3
194
6
6
157
37
9
133
24
12
126
7
15
116
10
18
110
6
21
92
18
24

12
27

9
30

4

1. Determine the average number of atoms remaining (not decayed) at each three-second time interval by adding the results from the two trials and dividing by two. 2. Create a table that compares time to the average number of atoms remaining at each time interval. 3. Create a graph of your data showing the average number of atoms remaining versus time. Conclusion

Answer the following questions in complete sentences.
1. After how many time intervals (shakes) did one-half of your atoms (candies) decay? 2. What is the half-life of your substance?
3. If the half-life model decayed perfectly, how many atoms would be
remaining (not decayed) after 12 seconds?

4. If you increased the initial amount of atoms (candies) to 300, would the overall shape of the graph be altered? Explain your answer.

5. Go back to your data table and for each three-second interval divide the number of candies decayed by the number previously remaining and multiply by 100. Show your work

. 6. The above percentage calculation will help you compare the decay modeled in this experiment to the half-life decay of a radioactive element. Did this activity perfectly model the concept of half-life? If not, was it close?

7. Compare how well this activity modeled the half-life of a radioactive element. Did the activity model half-life better over the first 12 seconds (four decays) or during the last 12 seconds of the experiment? If you see any difference in the effectiveness of this half-life model over time, what do you think is the reason for it?