DAY 1
• How many atoms of C-14 will be left in 120,000 years if the half-life is 40,000 years and there are 64 atoms?(Problem 1)
• If you have 1000 radioactive atoms now, how many radioactive atoms will be around in 3 half-lifes?(Problem 2)
• How many years have gone by in problem 2 if the half-life is 20 years?(Problem 3)
ANSWERS
• How many atoms of C-14 will be left in 120,000 years if the half-life is 40,000 years and there are 64 atoms?(Problem 1)
• Years atoms
• 0 64
• 40,000 32
• 80,000 16
• 120,000 8 Answer= 8 atoms
• If you have 1000 radioactive atoms now, how many radioactive atoms will be around in 3 half-lifes?(Problem 2)
• Half-lifes Atoms
• 0 1000
• 1 500
• 2 250
• 3 125 Answer= 125 atoms
• How many years have gone by in problem 2 if the half-life is 20 years?(Problem 3)
• Half-lifes Atoms Years
• 0 1000 0
• 1 500 20
• 2 250 40
• 3 125 60
• Answer= 60 Years
DAY 2
• How many atoms of U-238 will be left in 100,000 years if the half-life is 20,000 years and there are 128 atoms?(Problem 1)
• If you have 16,000 radioactive atoms now, how many radioactive atoms will be around in 3 half-lifes?(Problem 2)
• How many years have gone by if the half-life is 20 years, and 400 atoms decayed into 100 atoms?(Problem 3)
• How many atoms of U-238 will be left in 100,000 years if the half-life is 20,000 years and there are 128 atoms?(Problem 1)
• Years Atoms Half-life
• 0 128 0
• 20,000 64 1
• 40,000 32 2
• 60,000 16 3
• 80,000 8 4
• 100,000 4 5 ANS=4 atoms
If you have 16,000 radioactive atoms now, how many radioactive atoms will be around in 3 half-lifes?(Problem 2)
• Atoms Half-life
• 16,000 0
• 8,000 1
• 4,000 2
• 2,000 3
• Answer is 2000 atoms.
• How many years have gone by if the half-life is 20 years, and 400 atoms decayed into 100 atoms?(Problem 3)
• Atoms Half-life Years
• 400 0 0
• 200 1 20
• 100 2 40
• The answer is 40 years
DAY 3
• How many atoms of U-238 were around 60,000 years ago if the half-life is 20,000 years and there are currently 200 atoms? (Prob. 1)
• If you have 64,000 radioactive atoms now, how many radioactive atoms will be around in 8 half-lifes? (Problem 2)
• How many years have gone by if the half-life is 10 years, and 1600 atoms decayed into 200 atoms? (Problem 3)
• How many atoms of U-238 were around 60,000 years ago if the half-life is 20,000 years and there are currently 200 atoms?(Prob. 1)
• Years Atoms Half-life
• 0 200 0
• 20,000 400 1
• 40,000 800 2
• 60,000 1600 3
ANS=1600 atoms
• If you have 64,000 radioactive atoms now, how many radioactive atoms will be around in 8 half-lifes?(Problem 2)
• Atoms Half-life
• 64,000 0
• 32,000 1
• 16,000 2
• 8,000 3
• 4,000 4
• 2,000 5
• 1,000 6
• 500 7
• 250 8
• ANS=250 atoms
• How many years have gone by if the half-life is 10 years, and 1600 atoms decayed into 200 atoms?(Problem 3)
• Years Atoms Half-life
• 0 1600 0
• 10 800 1
• 20 400 2
• 30 200 3
• ANS= 30 years
DAY 4
• How many atoms of U-235 were around 4 million years ago if the half-life is 500,000 years and there is currently 1 atom? (Prob. 1)
• If you have 200,000 radioactive atoms now, how many radioactive atoms will be around in 4 half-lifes? How many were around 3 half-lifes ago? (Problem 2)
• How many years ago were there ½ the original atoms (parent isotopes) if the half-life is 10 years, and there are now 1/32 of the original atoms? (Problem 3)
• How many atoms of U-235 were around 4 million years ago if the half-life is 500,000 years and there is currently 1 atom?(Prob. 1)
• Years Atoms Half-life
• 0 1 0
• 500,000 2 1
• 1,000,000 4 2
• 1,500,000 8 3
• 2,000,000 16 4
• 2,500,000 32 5
• 3,000,000 64 6
• 3,500,000 128 7
• 4,000,000 256 8
ANS= 256 atoms
• If you have 200,000 radioactive atoms now, how many radioactive atoms will be around in 4 half-lifes? (Problem 2)
• Atoms Half-life
• 200,000 0
• 100,000 1
• 50,000 2
• 25,000 3
• 12,500 4
ANS= 12,500 atoms
• If you have 200,000 radioactive atoms now. How many were around 3 half-lifes ago? (Problem 2)
• Atoms Half-life
• 200,000 0
• 400,000 1
• 800,000 2
• 1,600,000 3
ANS= 1,600,000 atoms
• How many years ago were there ½ the original atoms(parent isotopes) if the half-life is 10 years, and there are now 1/32 of the original atoms? (Problem 3)
• Years Atoms Half-life
• 0 1/32 0
• 10 1/16 1
• 20 1/8 2
• 30 1/4 3
• 40 1/2 4
ANS= 40 years
DAY 5
• How many atoms of H-2 were around 40 years ago if the half-life is 10 years and there are currently 20 atoms?(Prob. 1)
• If you have 50,000 radioactive atoms now, how many radioactive atoms will be around in 2 half-lifes? How many were around 4 half-lifes ago? (Problem 2)
• How many years ago were there 128 atoms if the half-life is 1,000 years, and there are now 2 atoms? (Problem 3)
• How many atoms of H-2 were around 40 years ago if the half-life is 10 years and there are currently 20 atoms?(Prob. 1)
• Years Atoms Half-life
• 0 20 0
• 10 40 1
• 20 80 2
• 30 160 3
• 40 320 4
ANS= 320 atoms
• If you have 50,000 radioactive atoms now, how many radioactive atoms will be around in 2 half-lifes? How many were around 4 half-lifes ago? (Problem 2)
• Atoms Half-life
• 50,000 0
• 25,000 1
• 12,500 2
ANS= 12,500 atoms
• If you have 50,000 radioactive atoms now, how many radioactive atoms will be around in 2 half-lifes? How many were around 4 half-lifes ago? (Problem 2)
• Atoms Half-life
• 50,000 0
• 100,000 1
• 200,000 2
• 400,000 3
• 800,000 4
ANS= 800,000 atoms
• How many years ago were there 128 atoms if the half-life is 1,000 years, and there are now 2 atoms? (Problem 3)
• Years Atoms Half-life
• 0 2 0
• 1,000 4 1
• 2,000 8 2
• 3,000 16 3
• 4,000 32 4
• 5,000 64 5
• 6,000 128 6
ANS=6000 YEARS
DAY 6
• How many atoms of C-14 were around 160,000 years ago if the half-life is 40,000 years and there are currently 4 atoms?(Problem 1)
• If you have 1000 radioactive atoms now, how many radioactive atoms were around 4 half-lifes ago?(Problem 2)
• How many years have gone by in problem 2 if the half-life is 2000 years?(Problem 3)
• How many atoms of C-14 were around 160,000 years ago if the half-life is 40,000 years and there are currently 4 atoms?(Problem 1)
Time atoms
• 0 4
• 40,000 8
• 80,000 16
• 120,000 32
• 160,000 64 Answer= 64 atoms
• If you have 1000 radioactive atoms now, how many radioactive atoms were around 4 half-lifes ago?(Problem 2)
• Half-lifes Atoms
• 0 1000
• 1 2000
• 2 4000
• 3 8000
• 4 16,000 Answer= 16,000 atoms
How many years have gone by in problem 2 if the half-life is 2000 years?(Problem 3)
Half-lifes Atoms Time
• 0 1000 0
• 1 2000 2,000
• 2 4000 4,000
• 3 8000 6,000
• 4 16,000 8,000
• Answer= 8,000 years
DAY 7
• How many atoms of Po-208 were around 2 hours ago if the half-life is 20 minutes and there are currently 2000 atoms? (Prob. 1)
• If you have 64 radioactive atoms now, and in 10 days you have 16 atoms, what is the length of the half-life? (Problem 2)
• How many minutes have gone by if the half-life is 4 minutes, and 3200 atoms decayed into 50 atoms? (Problem 3)
• How many atoms of Po-208 were around 2 hours ago if the half-life is 20 minutes and there are currently 2000 atoms? (Prob. 1)
• Time Atoms Half-life
• 0 2,000 0
• 20 min. 4,000 1
• 40 min. 8,000 2
• 60 min. 16,000 3
• 80 min. 32,000 4
• 100 min. 64,000 5
• 120 min 128,000 6
ANS= 128,000 atoms
If you have 64 radioactive atoms now, and in 10 days you have 16 atoms, what is the length of the half-life? (Problem 2)
Atoms Half-life
• 64 0
• 32 1
• 16 2
• ANS=10 days/2 half-lifes= 5 days
• How many minutes have gone by if the half-life is 4 minutes, and 3200 atoms decayed into 50 atoms? (Problem 3)
• Minutes Atoms Half-life
• 0 3200 0
• 4 1600 1
• 8 800 2
• 12 400 3
• 16 200 4
• 20 100 5
• 24 50 6
• ANS= 24 minutes
DAY 8
• How many atoms of U-235 were around 1 million years ago if the half-life is 100,000 years and there is currently 4 atoms? (Prob. 1)
• If you have 1,000 radioactive atoms now, how many radioactive atoms will be around in 3 half-lifes? How many atoms were around 4 half-lifes ago? (Problem 2)
• How long is a half-life if 8000 atoms decay into 125 atoms in 18 years? (Problem 3)
• How many atoms of U-235 were around 1 million years ago if the half-life is 100,000 years and there is currently 4 atom? (Prob. 1)
• Time Atoms Half-life
• 0 4 0
• 100,000 8 1
• 200,000 16 2
• 300,000 32 3
• 400,000 64 4
• 500,000 128 5
• 600,000 256 6
• 700,000 512 7
• 800,000 1024 8
• 900,000 2048 9
• 1,000,000 4096 10
ANS= 4096 atoms
If you have 1,000 radioactive atoms now, how many radioactive atoms will be around in 3 half-lifes? How many atoms were around 4 half-lifes ago? (Problem 2) Atoms Half-life
• 1,000 0
• 500 1
• 250 2
• 125 3
ANS= 125 atoms
If you have 1,000 radioactive atoms now, how many radioactive atoms will be around in 3 half-lifes? How many atoms were around 4 half-lifes ago? (Problem 2)
Atoms Half-life
• 1,000 0
• 2,000 1
• 4,000 2
• 8,000 3
• 16,000 4
ANS= 16,000 atoms
• How long is a half-life if 8000 atoms decay into 125 atoms in 18 years? (Problem 3)
• Years Atoms Half-life
• 0 8,000 0
• 3 4,000 1
• 6 2,000 2
• 9 1,000 3
• 12 500 4
• 15 250 5
• 18 125 6
ANS= 18/6 =3 years