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Nuclear Chemistry Flashcards

1
Q

radioisotope

A

an isotope of an element that emits radiation caused by nuclear instability

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2
Q

stable isotopes

A

24 Mg 127I

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3
Q

examples of unstable isotopes

A

23Mg and 27Mg
125I and 131 I
235 U
238 U

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4
Q

alpha particle

A

4He2

2 protons and 2 neutrons are emitted as an alpha particle
mass number= 4
charge= 2+

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5
Q

beta particle

A

0e-1
a neutron changes to a proton and an electron is emitted

mass number= 0
charge= -1

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6
Q

positron

A

0e+1

a proton changes to a neutron and positron is emitted

mass number= 0
charge= 1+

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7
Q

gamma ray

A

γ

energy is lost to stabilise the nucleus

mass number= 1
charge= +1

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8
Q

proton

A

1H1

mass number= 1
charge= +1

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9
Q

neutron

A

1n0

a neutron is emiited

mass number= 1
charge= 0

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10
Q

what does ionizing radiation do?

A

it strikes molecules in its path and knocks away electrons in molecules forming unstable ions. it can cause undesirable chemical reactions.

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11
Q

effect of ionizing radiation on cells

A

damages the cells most sensitive to radiation, rapidly dividing cells in bone marrow, skin, and reproductive organs thus causing cancer

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12
Q

effect of ionizing radiation of DNA

A

ionising radiation forms unstable ions such as H2O+ which readily reacts with the electrons of the pi bond of the nitrogen bases of DNA which leads to mutations

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13
Q

penetration of alpha radiation

A

does not penetrate the human body

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14
Q

penetration of beta radiation

A

penetrated through living organs and tissues

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15
Q

penetration of gamma radiation

A

penetrates completely

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16
Q

radiation protection from alpha particles

A

paper and clothing

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17
Q

radiation protection from beta particles

A

lab coat and gloves

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18
Q

radiation protection from gamma rays

A

dense shielding such as lead and concrete

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19
Q

how can individuals who work in an environment where radioactive materials are present limit their exposure?

A
  1. minimizing the amount of time spent near a radioactive source
  2. increasing the distance from the source
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20
Q

what happens as you double your distance from the radiation source?

A

the intensity of the radiation drops to (1/2)^2

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21
Q

radioactive decay

A

the nucleus breaks down by emitting radiation

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22
Q

what is nuclear stability affected by?

A

the actual number of nucleons

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23
Q

which nuclei are always radioactive

A

Z>84

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24
Q

which number of protons and neutrons is more stable

A

an even number of protons and neutrons is more stable than odd

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25
what suggests the type of radioactive decay an isotope may undergo?
the ratio between the number of neutrons and the number of protons N/Z
26
N/Z too high
an isotope will tend to reduce the number of neutrons: beta decay
27
N/Z too low
the radioisotopes will undergo either positron emission or electron capture to reduce the number of protons and increase the number of neutrons
28
which is the heaviest element with at least one stable isotope?
Bismuth (Bi) Z =83
29
which number of neutrons/protons ensures the highest stability
N/Z = 2,8,20,28,50,82, 126
30
transmutation
when a stable nucleus is converted to a radioactive nucleus by bombarding it with a small particle
31
nuclear fission
with uranium, you obtain an unstable isotope that breaks down to lighter elements releasing large amounts of energy. in a chain reaction, there is a rapid increase in the number of high-energy neutrons available to react with more uranium
32
nuclear fusion
2 smaller nuclei combine to form a larger nucleus: the power of the sun
33
geiger count
detects beta and gamma radation uses ions produced by radiation to create an electrical current
34
units for measuring radiation
curie (Ci) becquerel (Bq) rad (radiation absobed dose) rem (radiation equivalent in humans)
35
curie (Ci)
the number of disintegrations that occurs in 1s for 1g of radium equal to 3.7 x 10^10 disintegrations/s
36
becquerel (Bq)
the SI unit of radiation activity which is 1 disintegration/s
37
rad (radiation absorbed dose)
measures the amount of radiation absorbed by a gram of material such as body tissue
38
rem (radiation equivalent in humans)
measures the biological effects of different kinds of radiation
39
what does rem measure?
1. alpha particles: which do not penetrate the skin 2. high energy radiation: which causes more damage than alpha particles and includes beta particles, high-energy protons and neutrons 3. gamma radiation
40
how to determine the equivalent dose/ rem dose
biological damage (rem) = absorbed dose (rad) x factor
41
what is the factor in the equation to determine the equivalent/rem dose for beta and gamma radiation
1
42
what is the factor in the equation to determine the equivalent/rem dose for high-energy protons and neutrons
10
43
what is the factor in the equation to determine the equivalent/rem dose for alpha particles
20
44
what is the SI unit for equivalent dose?
sievert (Sv)
45
how many rem is 1Sv?
1Sv= 100rem
46
what has the FDA approved?
approved the dose of 0.3kGy to 1kGy of radiation produced by cobalt-60, and cesium 137 for the treatment of foods. gamma rays pass through the food and kill the bacteria without harming the food to prevent foodborne illnesses
47
what happens to tomatoes, blueberries, strawberries and mushrooms?
they are being irradiated to allow them to be harvested when they are completely ripe to extend their shelf life
48
what do people who work in radiation laboratories wear?
dosimeters
49
dosimeters
detect the amount of radiation exposrure from X-rays, gamma rays and beta particles
50
how much is the average person exposed to radiation
360mrem= 3.6mSv annually
51
where do we get exposure to radiation
- buildings where we live and work - food and water - the air we breathe
52
sources of naturally occurring isotopes
- potassium 40 in potassium-containing foods - cosmic radiation from the sun
53
lethal dose LD50
exposure to radiation of 500 rem is expected to cause death in 50% of the people receiving the dose
54
which radiation exposure cannot be detected?
less than 0.25 Sv
55
half-life of a radioisotope
the time for the radiation level to decrease to one-half of the original value
56
list the significance of C-14
- incorporated in CO2: fixated in organic compounds through photosynthesis - can be used to date artifacts of organic origin dating up to 40-60,000 years ago
57
carbon-14 decay
decays via beta emission too N-14 with a half-life of 5730 years
58
why are radioisotopes with short half-lives used in medicine?
1. the cells in the body do not differentiate between non-radioactive atoms and radioactive atoms 2. once incorporated into cells, the radioactive atoms are detected because they emit radiation, giving an image of an organ
59
what happens after a radioisotope is ingested by the patient
1. the scanner moves slowly over the organ where the radioisotope is absorbed 2. the radiologist determines the level and location of the radioactivity emitted by the radioisotope 3. the gamma rays emitted from the radioisotope can be used to expose a photographic plate, producing a scan of the organ
60
positron emission tomography
used to study brain function, metabolism, and blood flow
61
how does a PET work
it utilizes positron emitters with short half-lives. might be carbon-11, oxygen-15, nitrogen-13 or fluorine-18. it combines with electrons after emission to produce gamma rays, which are then detected by computers creating a 3d image of the activity of the organ
62
computed tomography CT
used to scan organs such as the brain, lungs, and heart
63
how does a CT scan work
a computer monitors the absorption X-ray beams directed at the organ in successive layers
64
Magnetic Resonance Imaging
does not involve X-ray radiation. it is based on the absorption of energy when protons in hydrogen atoms are excited by a strong magnetic field.
65
brachytherapy
internal form of radiation therapy
66
permanent brachytherapy
- involves the implantation of 40 or more titanium capsules/seeds in the malignant area - utilises I 125, Pa 103, and Ce 131 in the seeds which decay by gamma emission - the radiation from the seeds destroys the cancer by interfering with the reproduction of cancer cells
67
what is brachytherapy used for
treatment option for prostate cancer in males
68
temporary brachytherapy
- involves the implantation of long needles containing iridium-192 in the tumor - can be used to deliver a higher dose of radiation over a shorter time

Medicinal Chemistry (10 decks)

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