Data and Observations

**08.01 Half-Life and Radioactive Decay: Half-Life lab**

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.

Calculations

1) After how many time intervals (shakes) did one-half of your atoms (candies) decay?

It took around 2 shakes for one-half of my atoms(candies) to decay.

2)What is the half-life of your substance?

The half-life of my substance is 3 seconds.

3) If the half-life model decayed perfectly, how many atoms would be remaining (not decayed) after 12 seconds?

If the model decayed perfectly there should have been only 12.5 atoms or 13 if the count was rounded up.

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

Not necessarily as the amount of graph will still be in a downward slope, however the time interval would have increased.

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.

**Conclusion Questions**

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.

Table 1: 0/200*100=0%,

98/200*100=49%,

51/102*10=50%,

23/102*100=23%,

16/51*100=31%,

7-51*100=14%,

3/28*100=11%,

0/28*100=0%,

1/12*100=8%,

1/12*100=8%,

0/5*100=0%

Table 2: 0/200*100=0%,

91/200*100=46%,

50/107*100=47%,

23/107*100=21%,

18/57*100=32%,

10/57*100=18%,

3/34*100=9%,

2/34*100=6%,

0/16*100=0%,

1/16*100=6%,

0/6*100=0%.

Conclusion 2

Atoms

not decayed

Atoms

Decayed

0

3 sec

6 sec

9 sec

12 sec

15 sec

18 sec

21 sec

24 sec

27 sec

30 sec

200

102

51

28

12

5

2

2

1

0

0

0

98

51

23

16

7

3

0

1

1

0

Time

(seconds)

Average number of

atoms remaining

0

200

3

104.5

6

9

12

15

18

21

24

27

30

54

31

14

5.5

2.5

1.5

1

0

0

Calculations extended

Conclusion 3

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?

The activity attempted to model half life pretty well. Over all the results were pretty close and the candies were decayed almost accurately. For example in the first trial, the candies were decayed almost completely in half representing half-life very well.

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?

There was no clear difference in the last or first 12 seconds of the activity, it started off decaying half of the candies or atoms and ended the same way. Starting with 0 and ending with 0.