IMS EIGHTH GRADE SCIENCE NAME

ACTIVITY #___ NAME(S): ____________

DEMONSTRATING HALF-LIFE PERIOD: _____

BACKGROUND INFORMATION: DATE: ______ Score: ___

Academic Standards: 3.1, 3.4, 3.5, 3.6, 3.8

THE HALF-LIFE OF A RADIOACTIVE ELEMENT IS THE AMOUNT OF TIME IT TAKES FOR ONE-HALF OF THE ATOMS IN A SAMPLE OF THAT ELEMENT TO DECAY, OR BREAK DOWN INTO ATOMS OF THE STABLE DECAY ELEMENT. RADIOACTIVE DECAY IS ONE OF THE METHODS SCIENTISTS USE TO MEASURE GEOLOGICAL TIME AND DETERMINE THE ABSOLUTE AGE OF ROCKS AND FOSSILS.

IN THIS INVESTIGATION, YOU WILL DEVELOP A SIMULATION, OR MODEL, FOR THE HALF-LIFE OF A RADIOACTIVE ELEMENT.

PROCEDURE: YOU NEED ONE 500 ML BEAKER, ONE GRADUATED CYLINDER, CLOCK,
___ ( 100 )ML OF RADIOACTIVE ELEMENT X, FOOD COLORING

1. ADD FOOD COLORING TO THE GRADUATED CYLINDER, TO MAKE THE RADIO ACTIVE SUBSTANCE.

2. FILL THE GRADUATED CYLINDER, WITH ____ (100 )ML OF WATER.

3. RECORD THE HALF LIFE OF YOUR GROUPS RADIOACTIVE ELEMENT X (circle one).

YOUR COLOR IS (Circle one) RED, GREEN, BLUE, YELLOW, CLEAR.

YOUR HALF-LIFE TIME IS: (Circle one) (30, 45, 60, 1 MIN 15 SEC, 1 MIN 30 SEC)

4. TO ILLUSTRATE EACH HALF-LIFE, USE THE GRADUATED CYLINDER TO DIVIDE THE RADIOACTIVE ELEMENT IN HALF EVERY TIME A HALF-LIFE PERIOD ENDS. POUR THE PORTION OF THE RADIOACTIVE ELEMENT THAT HAS DECAYED INTO THE BEAKER.

FOR EXAMPLE, IF THE HALF-LIFE IS 30 SECONDS, EVERY 30 SECONDS DIVIDE THE RADIOACTIVE ELEMENT IN THE GRADUATED CYLINDER IN HALF.

5. FOLLOW THE DECAY OF YOUR RADIOACTIVE ELEMENT THROUGH ALL HALF-LIFES. COMPLETE THE DATA TABLE AS YOU WORK.

6. GRAPH YOUR DATA ON THE GRAPH PROVIDED. BE SURE TO FILL IN THE NUMBERS ON THE TIME PASSED (MIN- SEC) AXIS.

SELECT NUMBERS THAT ARE APPROPRIATE FOR YOUR HALF-LIFE.

7. REPORT RESULTS TO THE CLASS DURING CLASS DISCUSSION.

8. DO THE CONCLUSION QUESTIONS.

9. SEE THE OTHER THE HANDOUT RADIOACTIVE DECAY SIMULATION AND COMPLETE THIS SIMULATION EXERCISE (TI- 83 program- HALFLIFE).

Half-Life- _____ sec.	Amount Radioactive	Amount decayed	Total Time (seconds)
1	100 ml.	50 ml	sec
2	50 ml	ml	sec
3	ml	ml	sec
4	ml	ml	sec
5	ml	ml	sec
6	ml	ml	sec
7	ml	ml	sec
8	ml	ml	sec
9	ml	ml	sec
10	ml	ml	sec

GRAPH: Answers will vary. (Circle one)

Your radioactive color was: RED, GREEN, BLUE, YELLOW, CLEAR

YOUR HALF-LIFE TIME IS (30, 45, 60, 1 MIN 15 SEC, 1 MIN 30 SEC )

Graph represents the data from the data table taken to tenth half-life.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
2.5
1.25
0
	30	60	90	120	150	180	210	240	270	300	330	360	390	420	450	480	510	540	570	600

Conclusions:

1. What was radioactive the filled graduated cylinder or the 500 ml beaker? _____________________

2. What contained the decayed element, the filled graduated cylinder or the 500 ml beaker? _______

3. By what amount does the volume of the graduated cylinder decrease for each time period? ______

4. Does the shape of your graph resemble the shapes of graphs of your classmates? _____________

If yes why? ____________________________________________________________________________

If no why? _____________________________________________________________________________

5. What was the total time that you could continue to measure with the graduated cylinder? ______ s

6. How many half-life’s are possible if we could continue to measure? _____________