Chemistry 115
Lecture 5 Outline
Chapter 24
Nuclear Transmutation
Radiation, Dosages
Nuclear Medicine
HW3: Due Friday, Jan ...
Nuclear Transmutation
Nuclear transmutation – transform 1 element into
another - like Alchemy
Example:
14
7N + 4
2He  1
1...
Linear Accelerator
Fig. 24.7
Ion Cyclotron
Inside a large accelerator
Nuclear Transmutations
Radiation
Radiation when it interacts with matter can cause two
effects:
Non-ionizing radation – causes atoms to vibrate m...
Radiation Penetrating Power
Units of Radioactivity
Activity or disintegrations (transformations) per unit
of time is expressed in units of curies (Ci)...
Units of Dose
Not all types of radiation are absorbed to the same
extent. Different types of radiation deposit different
a...
Radiation Equivalents
Particle Relative energy deposited
Relative Biological Effectiveness
γ 1
e-
1
1
1p 5
1
0n 1 - 100
4
...
Radiation Damage
1 gy = 1 J/kg
4 gy/ 1 g H2O raises the temperature by 4o
C
Radiation damage is not due to heating, it res...
Radiation Damage
The body can handle and repair a certain amount of free
radical damage whether it is caused by radiation,...
Radiation Damage
The body can handle a certain amount of free radicals before
the free radicals overwhelm the body's free ...
Nuclear Medicine
Nuclear medicine:
•uses radioactive substances (radiopharmaceuticals)
•radioactive substances are adminis...
99
Mo → 99m
Tc + e- 99
Mo: t1/2 = 66 h
99m
Tc → 99
Tc + γ 99m
Tc: t1/2 = 6 h
γ-rays behave like x-rays,
they pass through ...
Thyroid Images
131
I 99
Tc
Nuclear Reactions
Positron Emission, β+
-decay
Positron Emission: decay by loss of an a positron, a
particle with the same...
PET
Positron Emission Tomography
β+
+ β-
→ 2 γ (0.511 MeV each, in opposite directions)
Nuclear Chemistry: PET Imaging
PET
18
O + 1
p → 18
F + 1
n 18
F → 18
O + e+
Brain with blunt force trauma
DNA mapping
32
15P: Image DNA fragments
Photographic image formed from decay of 32
P
1-22-08
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  • 1-22-08

    1. 1. Chemistry 115 Lecture 5 Outline Chapter 24 Nuclear Transmutation Radiation, Dosages Nuclear Medicine HW3: Due Friday, Jan 25 (Quiz 2) Recitation: Ch 24: Radioactive Decay. Nuclear Stability Radiation Dosage, Nuclear Medicine Binding Energy, Nuclear Power
    2. 2. Nuclear Transmutation Nuclear transmutation – transform 1 element into another - like Alchemy Example: 14 7N + 4 2He  1 1H + 17 8O Rutherford, 1919 This led to the discovery of the neutron – like a gamma ray (neutral charge), but heavy like a proton. This approach is used to make the transuranium elements And studied in accelerators
    3. 3. Linear Accelerator
    4. 4. Fig. 24.7 Ion Cyclotron
    5. 5. Inside a large accelerator
    6. 6. Nuclear Transmutations
    7. 7. Radiation Radiation when it interacts with matter can cause two effects: Non-ionizing radation – causes atoms to vibrate matter gains heat Ionizing radiation – causes loss of electron(s): Atom  ion+ + e- This type of radiation can be dangerous because it causes reactive radical species.
    8. 8. Radiation Penetrating Power
    9. 9. Units of Radioactivity Activity or disintegrations (transformations) per unit of time is expressed in units of curies (Ci) or in the SI unit of becquerels (Bq) One becquerel = 1 disintegration per second (s-1 ). One curie = 3.7 x 1010 disintegrations per second = 3.7 x 1010 becquerels
    10. 10. Units of Dose Not all types of radiation are absorbed to the same extent. Different types of radiation deposit different amounts of energy when absorbed by the body. A Gray is the SI unit of absorbed dose. gy = 1 joule / kg of body tissue = 100 rads
    11. 11. Radiation Equivalents Particle Relative energy deposited Relative Biological Effectiveness γ 1 e- 1 1 1p 5 1 0n 1 - 100 4 2He 20 rem = RBE x rads
    12. 12. Radiation Damage 1 gy = 1 J/kg 4 gy/ 1 g H2O raises the temperature by 4o C Radiation damage is not due to heating, it results from breaking chemical bonds in a body producing free radicals. Free radical, unpaired e-
    13. 13. Radiation Damage The body can handle and repair a certain amount of free radical damage whether it is caused by radiation, drinking alcohol, heavy labor, heavy exercise, eating slightly rancid food, or from wounds. Radiation sickness is a free radical disease just as a hang-over is.
    14. 14. Radiation Damage The body can handle a certain amount of free radicals before the free radicals overwhelm the body's free radical scavenging system. When overwhelmed, part of the free radical damage consists of damage to the body's free radical scavenging system creating a vicious cycle. Radiation kills by breaking cells DNA. As a consequence, cells can no longer reproduce. LD50 is approximately 2.5 - 4 Gy (250 – 400 rem) depending on length of exposure and treatment.
    15. 15. Nuclear Medicine Nuclear medicine: •uses radioactive substances (radiopharmaceuticals) •radioactive substances are administered and the radiation emitted is measured •usually involves the formation of an image •radionuclides are also administered to treat disease or provide pain relief. •iodine-131 is often used for the treatment of thyrotoxicosis and thyroid cancer.
    16. 16. 99 Mo → 99m Tc + e- 99 Mo: t1/2 = 66 h 99m Tc → 99 Tc + γ 99m Tc: t1/2 = 6 h γ-rays behave like x-rays, they pass through tissue. Cardiolite distributes in the heart proportionally to the blood flow in the heart’s muscle
    17. 17. Thyroid Images 131 I 99 Tc
    18. 18. Nuclear Reactions Positron Emission, β+ -decay Positron Emission: decay by loss of an a positron, a particle with the same mass as an electron but with a positive charge (a positive electron). 11 6C → 11 5B + 0 1e The positron interacts with an electron, and the two annihilate each other. All of their mass is converted into energy––two 0.511 MeV gamma rays are produced. 0 –1e + 0 +1e → 2 γ (0.511 MeV each)
    19. 19. PET Positron Emission Tomography β+ + β- → 2 γ (0.511 MeV each, in opposite directions)
    20. 20. Nuclear Chemistry: PET Imaging
    21. 21. PET 18 O + 1 p → 18 F + 1 n 18 F → 18 O + e+ Brain with blunt force trauma
    22. 22. DNA mapping 32 15P: Image DNA fragments Photographic image formed from decay of 32 P

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