2 - 1 ch 104 chapter 5: nuclear chemistry radioactivity nuclear equations radiation detection...
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2 - 1CH 104
Chapter 5: Nuclear Chemistry
RadioactivityNuclear Equations
Radiation DetectionHalf-Life
Medical Applications
2 - 2CH 104
Isotopes of HydrogenIsotopes = Atoms of the same element but
having different masses.
11
21
31
H H H
+
-
+
-
+
-
Protium99.99%
Deuterium0.01%
TritiumTrace %
Average Atomic weight of Hydrogen = 1.00794 amu
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Isotopes of Carbon
Average Atomic weight of C= 12.011 amu
98.89%
C612 C6
13C6
14
1.11% Trace %
++
++
+ +
-
-
-
-
--
-
++
++
+ +
-
-- -
-+
+
++
+ +
-
-
-
--
-
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Radioactive Isotopes
C614
++
++
+ +
-
-
-
--
-+
31
H-
Nucleus is unstableSo falls apart (decays)
Giving radioactive particles
Hydrogen-3Carbon-14
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Radioactive Isotopes in Medicine
Tc43
99m
123 53
I
131 53
I
6027
Co
Diagnose thyroid function
Treat hyperthyroid (destroys cells)
Destroy tumors (g radiation)
Diagnose bone, tissue (most common)
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Alpha Decay
Pb82206 +
+
++
+ +
21084 Po
42
He + +
a Particle
21084 Po Pb82
206 + 42 He
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Beta Decay
N714
146 C
0-1
e -
b Particle+
+
++
+ + ++
++
+ ++
+ -
10
n11
H +0-1
eneutron proton electron
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Beta Decay
N714
146 C
0-1
e -
b Particle+
+
++
+ + ++
++
+ ++
+ -
+0-1e14
6 C N714
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Gamma Decay
99m43 Tc g decay
++
++
+ + ++
++
+ +
9943 Tc
+99m43 Tc Tc43
99 g
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Ionizing Radiation
O HH O HH
-Radiation knocks off an electron
Radiation knocks off an electron
An ionAn ion
C HH
H
H
C HH
H
H
A radicalA radical
Ions & radicals cause damaging chain reactionsIons & radicals cause damaging chain reactions
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Geiger Counter
-
Radiation knocks off an electron
Radiation knocks off an electron
An ionAn ion
Ions detected by Counter
Ions detected by Counter
ArArGas in
instrument tube
Gas in instrument
tube
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Radiation: Penetration through Air
+ +a
-b
g
2 - 4 cm
200 - 300 cm
500 m
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Radiation: Shielding
+ +a
-b
g
Paper Cloth
Heavy Cloth
Pb, thick concrete
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+ +a
-b
g
Tissue Penetration Depth
0.05 mm
4-5 mm
>50 cm
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Nuclear Equations
22688 Ra Rn86
222 + 42 He
: a Radon gas in Buildings
Po84218 + 4
2 He
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13153 I Xe54
131 + 0-1e
: b Thyroid check & treatment
: b Cancer Treatment Nuclear Equations
6027 Co Ni28
60 + 0-1e
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Radiation Detection
1 Ci = 3.7 x 1010disintegrations sec
1 Bq = 1 disintegration sec
# of disintegrations by of 1g Ra
ActivityActivity
Becquerel (Bq)
Curie (Ci):
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Radiation Detection
Absorbed DoseAbsorbed Dose
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+ +a
-b
g
Tissue Penetration Depth0.05 mm
0.06-5 mm
>50 cm
Radiation Absorbed Dose (Rad) (D):
1 rad = 1 x 10-2 J kg tissue
1 rad = 1 x 10-2 J kg tissue
1 rad = 2.4 x 10-3 cal kg tissue
Radiation Detection: Biological Effect
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+ +a
-b
g
Tissue Penetration Depth0.05 mm
0.06-5 mm
>50 cm
Radiation Absorbed Dose (Rad) (D):
1 Gray = 1 J kg tissue
1 Gray = 1 J kg tissue
100 rad = 1 Gray
Radiation Detection: Biological Effect
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Radiation Detection
Biological Damage Biological Damage
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Radiation Equivalent for Man (rem)
a
b
g
1 rem = 1 rad x RBE
RBE20
1
1
RBE20
1
1
Damage (rem) = absorbed dose (rad) X factor
(relative biological effectiveness)
100 rem = 1 sievert (Sv)
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Learning Check
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Learning Check: Solution
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Annual Radiation Exposure in USA
Ground = 15 mrem
Air, H2O, Food = 30 mremCosmic = 40 mrem
Wood,concrete,bricks = 50 mrem
X-rays: Chest = 50 mremDental = 20
Smoking = 35 mrem
TV = 2 mrem
Radon = 200 mrem
Total = 170 mrem / yrTotal = 170 mrem / yr
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Annual Radiation Exposure in USA
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Biological Effects of Radiation
Dose in rem (at one time)0-25 genetic damage possible but usually undetected
25-100 decrease # of white blood cells (temporary)
100-200 mild radiation sickness (vomit, diarrhea, strong decrease # white blood cells)
>300 (diarrhea, hair loss, infection)
500 LD50 for humans
Dose in rem (at one time)0-25 genetic damage possible but usually undetected
25-100 decrease # of white blood cells (temporary)
100-200 mild radiation sickness (vomit, diarrhea, strong decrease # white blood cells)
>300 (diarrhea, hair loss, infection)
500 LD50 for humans
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300 LD50 for dogs
800 LD50 for rats
50,000 LD50 for Bacterium
100,000 LD50 for Insects
Biological Effects of RadiationDose in rem
500 LD50 for humans
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4,500 Lymphoma
5,000 – 6,000 Skin cancer
6,000 Lung cancer
6,000 – 7000 Brain Tumor
Therapeutic Doses of RadiationDose in rem
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FDA approved killing of bacteria with:
0.3 – 1 kGy ionizing radiation from
Co-60 or Cs-137(gamma producers)
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Half-Life
t1/2 = Time for 1/2 sample to decay
13153 I
20 g
t1/2 =
8 days10 g
8 days
5 g
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Half-Life
I-131 8 days
Co-60 5.3 yrs
Tc-99m 6 hrs
I-131 8 days
Co-60 5.3 yrs
Tc-99m 6 hrs
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Half-Life
t1/2 = Time for 1/2 sample to decay
13153 I
20 g
t1/2 =
8 days10 g
8 days
5 g
Youtube: Bill Nye Explains Half Life (1:04)https://www.youtube.com/watch?v=js7weHZIQ5o
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B511
116 C
0+1e +
10
n11
H +0+1
e
proton neutron positron
Positron Emission Tomography (PET)
b+ Positron+
+
+
+ ++0
++
+
+ +0
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g rays image
Shows blood flow
g rays image
Shows blood flowB5
11
116 C
0+1e +
Positron Emission Tomography (PET)
b+ Positron+
+
+
+ ++0
++
+
+ +0
115 B
116 C +
0+1
e
positron
0-1e
electron
2g raysDetectable
-
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g rays image
Shows blood flow
g rays image
Shows blood flowB5
11
116 C
0+1e +
Positron Emission Tomography (PET)
b+ Positron+
+
+
+ ++0
++
+
+ +0
0-1e
electron
2g raysDetectable
-
2g+0+1e
electron gammapositron
0-1e
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Radiometric DatingC-14 dating of artifacts (bones, wood,….); t½ = 5760 years
+0-1e14
6 C N714
Issues:• Production of C-14 by sun varies in atmosphere.• 14CO2(g) amounts vary in atmosphere
U-238 Pb-206 U-235 Pb-207Issues:• Assumes all Pb was once U
K Ar(t ½ K-40 = 1.248 x 109 years)
+4020Ca40
19 K Ar1840
2Issues:• Ar(g) solubility• Starting amount of K-40
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Learning Check
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Learning Check: Solution
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Videos
Video: Frontline NOVA Fukushima: Nuclear Aftershocks (53.41 min)http://video.pbs.org/video/2187854464/
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Learning Check: Chromium-55 undergoes beta decay wth a half life of 3.5 minutes.
What is the primary identity of the sample after decay?
5524 Cr +
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Learning Check: Solution Chromium-55 undergoes beta decay wth a half life of 3.5 minutes.
What is the primary identity of the sample after decay?
5524 Cr Mn25
55 + 0-1e
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Learning Check: Chromium-55 undergoes beta decay wth a half life of 3.5 minutes.
What is the primary identity of the sample after decay?
If you start with 120 g; How much Cr-55 will be left after 14 minutes?
5524 Cr Mn25
55 + 0-1e
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Learning Check: Solution Chromium-55 undergoes beta decay wth a half life of 3.5 minutes.
5524 Cr
120 g
t1/2 =
3.5 min
60 g
3.5 min
What is the primary identity of the sample after decay?
If you start with 120 g; How much Cr-55 will be left after 14 minutes?
5524 Cr Mn25
55 + 0-1e
(7 min Total)
3.5 min
(10.5 min Tot)
3.5 min
(14 min Total)
30 g 15 g 7.5 g