the amount of time it takes half of a radioactive sample to decay Total Time HalfLife Fraction of Radioactive Atoms Remaining Fraction of Radioactive Atoms Decayed 0 ID: 713554
Download Presentation The PPT/PDF document "Half-Life Notes Half-Life" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Half-Life NotesSlide2
Half-Life
: the amount of time it takes half of a radioactive sample to decay.
TotalTimeHalf-Life #Fraction of Radioactive Atoms RemainingFraction of Radioactive Atoms Decayed 0 1 2 3 4 5 6
½
½
¼
¾
1/8
7/8
1/16
15/16
1/32
31/32
1/64
63/64
1
0
Slide3
Example 1) Assuming a half-life of 1599 years, how many years will be needed for the decay of 15/16 of a given amount of radium-226?
Need
4 half-lives4 * 1599 years = 6396 yearsTotalTimeHalf-Life #Fraction of Radioactive Atoms RemainingFraction of Radioactive Atoms Decayed 0 1 2 3 4 ½ ½ ¼ ¾ 1/8 7/8 1/16 15/16 1 0 0 yrs1599 yrs3198
yrs
4797 yrs
6396
yrsSlide4
Example 2) The half-life of radon-222 is 3.824 days. How much time must past for ¼ of a given amount of radon to remain?
Need 2 half-lives
2 * 3.824 days= 7.648 daysTotalTimeHalf-Life #Fraction of Radioactive Atoms RemainingFraction of Radioactive Atoms Decayed 0 1 2 ½ ½ ¼ ¾ 1 0 0 days3.824 days7.648 daysSlide5
Example 3) The half-life of polonium-218 is 3.0min. If you start with 16mg of polonium-218, how much time must pass for only 1.0mg to remain?
Starting Amount = 16 mg
Remaining Amount = 1.0 mgFraction Remainig = 1.0 / 16 mg = 1/16TotalTimeHalf-Life #Fraction of Radioactive Atoms RemainingFraction of Radioactive Atoms Decayed 0 1 2 3 4 ½ ½ ¼ ¾ 1/8 7/8 1/16 15/16 1 0 0 min
3.0 min
6.0 min
9.0 min
12 min
Need 4 half-lives
4* 3.0min = 12 minSlide6
After 4797 years, how much of an original 0.250g sample of radium-226 remains? Its half-life is 1599 years. Slide7
The half-life of radium-224 is 3.66 days. What was the original mass of radium-224 if 0.0800g remains after 7.32 days?