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Chapter 5: Nuclear Chemistry

5.1: Natural Radioactivity

  • An unstable nucleus is radioactive, which means that it spontaneously emits small particles of energy called radiation to become more stable.

  • Radioisotope: An isotope of an element that emits radiation.

  • Atomic Symbols: Written with the mass number in the upper left corner and the atomic number in the lower left corner.

  • Mass Number: The sum of the numbers of protons and neutrons in the nucleus.

  • Atomic Number: It is equal to the number of protons.

Types of Radiation

  • Alpha Particle: It has two protons and two neutrons.

    • It has a mass number of 4, an atomic number of 2, and a charge of 2+.

  • Beta Particle: It is a high-energy electron, has a charge of 1–, and it has a mass number of 0.

    • It is formed when a neutron in an unstable nucleus changes into a proton.

  • Positron: It has a positive charge with a mass number of 0.

    • It is produced by an unstable nucleus when a proton is transformed into a neutron and a positron.

    • Antimatter: A particle that is the opposite of another particle — an electron.

  • Gamma Rays: These are high-energy radiation, released when an unstable nucleus undergoes a rearrangement of its particle to give a more stable, lower-energy nucleus.


5.2: Nuclear Reactions

  • Radioactive Decay: A process where a nucleus spontaneously breaks down by emitting radiation.

  • Alpha Decay: An unstable nucleus may emit an alpha particle, which consists of two protons and two neutrons.

    • The mass number of the radioactive nucleus decreases by 4, and its atomic number decreases by 2.

    • Americium-241: Mostly found in smoke detectors used in homes and apartments, which undergoes alpha decay.

  • Beta Decay: The formation of beta particles results from the breakdown of a neutron into a proton and an electron.

    • The mass number of the radioactive nucleus and the mass number of the new nucleus is the same.

    • Radioactive Isotope Yttrium–90: A beta emitter, is used in cancer treatment and as a colloidal injection into large joints to relieve the pain of arthritis.

  • Positron Emission

    • A proton in an unstable nucleus is converted to a neutron and a positron.

    • The neutron remains in the nucleus, but the positron is emitted from the nucleus.

    • The mass number of the radioactive nucleus and the mass number of the new nucleus is the same.

    • The atomic number decreases by one, indicating a change in one element into one another.

  • Gamma Emission: Pure gamma emitters are rare, although gamma radiation accompanies most alpha and beta radiation.

  • Transmutation: A stable nucleus is bombarded by high-speed particles such as alpha particles, protons, neutrons, and small nuclei.


5.3: Radiation Measurements

  • When a radiology laboratory obtains a radioisotope, the activity of the sample is measured in terms of the number of nuclear disintegrations per second.

  • Curie (Ci): The original unit of activity.

    • It was defined as the number of disintegrations that occurs in 1 s for 1 g of radium, which is equal to 3.7 ✕ 10^10 disintegrations/s.

    • It was named after Marie Curie and her husband, Pierre, who discovered the radioactive elements; radium and polonium.

  • Becquerel (Bq): The SI unit of radiation activity, is 1 disintegration/s.

  • Radiation Absorbed Dose (Rad): A unit that measures the amount of radiation absorbed by a gram of a material such as body tissue.

  • Gray (Gy): The SI unit for absorbed dose.

    • The joules of energy absorbed by 1 kg of body tissue/

    • It is equal to 100 rad.

  • Radiation Equivalent in Humans (Rem): A unit that measures the biological effects of different kinds of radiation.

    • To determine the equivalent dose or rem dose, the absorbed dose (rad) is multiples by a factor that adjusts for biological damage caused by a particular form of radiation.

  • Sievert (Sv): The SI unit for the equivalent dose or biological damage.

    • One sievert is equal to 100 rem.

  • Lethal dose for one-half of the population: The amount of radiation to the whole body; the LD50.


5.4: Half-Life of a Radioisotope

  • Half-Life: The amount of time it takes for one-half of a sample to decay.

  • Decay Curve: A diagram of the decay of a radioactive isotope.

  • Phosphorous: A radioisotope used in the treatment of leukemia has a half-life of 14.3 days.

  • Radiological dating: A technique used by geologists, archaeologists, and historians to determine the age of ancient objects.

  • Carbon Dating (Carbon-14): The method for determining the age of an object containing organic material is by using the properties of radiocarbon, a radioactive isotope of carbon.


5.5: Medical Applications Using Radioactivity

  • Scanner: An apparatus used to produce an image of the organ.

    • The gamma rays emitted from the radioisotope in the organ can be used to expose a photographic plate, producing a scan of the organ.

  • Radioactive iodine uptake: The standard method of determining thyroid function.

  • Positron emission tomography (PET)

    • An imaging method where Positron emitters with short half-lives such as carbon-11, oxygen-15, nitrogen-13, and fluorine-18 are used.

    • Positron-Emitting Isotopes: These are used to study brain function, metabolism, and blood flow.

  • Computed Tomography (CT) Scan

    • Another imaging method is used to scan organs such as the brain, lungs, and heart.

    • A computer monitors the absorption of 30 000 X-ray beams directed at successive layers of the target organ.

    • This technique is successful in the identification of hemorrhages, tumors, and atrophy.

  • Magnetic resonance imaging (MRI)

    • A powerful imaging technique that does not involve X-ray radiation.

    • It is based on the absorption of energy when the protons in hydrogen atoms are excited by a strong magnetic field.

  • Brachytherapy

    • Also known as seed implantation.

    • It is an internal form of radiation therapy.

    • With internal radiation, a high dose of radiation is delivered to a cancerous area, while normal tissue sustains minimal damage.

Medical Applications of Radioisotopes

Isotope

Half-Life

Radiation

Medical Application

Au-198

2.7 days

Beta

Liver imaging; treatment of abdominal carcinoma

Ce-141

32.5 days

Beta

Gastrointestinal tract diagnosis; measuring blood flow to the heart

Cs-131

9.7 days

Gamma P

Prostate brachytherapy

F-18

110 min

Positron

Positron emission tomography (PET)

Ga-67

78 h

Gamma

Abdominal imaging; tumor detection

Ga-68

68 min

Gamma

Detection of pancreatic cancer

I-123

13.2 h

Gamma

Treatment of thyroid, brain, and prostate cancer

I-131

8.0 days

Beta

Treatment of Graves’ disease, goiter, hyperthyroidism, thyroid and prostate cancer

Ir-192

74 days

Gamma

Treatment of breast and prostate cancer

P-32

14.3 days

Beta

Treatment of leukemia, excess red blood cells, pancreatic cancer

Pd-103

17 days

Gamma

Prostate brachytherapy

Sr-85

65 days

Gamma

Detection of bone lesions; brain scans

Tc-99m

6.0 h

Gamma

Imaging of skeleton and heart muscle, brain, liver, heart, lungs, bone, spleen, kidney, and thyroid; most widely used radioisotope in nuclear medicine

Y-90

2.7 days

Beta

Treatment of liver cancer


5.6: Nuclear Fission and Fusion

  • Atomic Energy: The energy generated by splitting the atom.

  • During the 1930s, scientists bombarding uranium-235 with neutrons discovered that the U-235 nucleus splits into two smaller nuclei and produces a great amount of energy; which led to the discovery of — nuclear fission.

  • Chain Reaction: A fission reaction that will continue once it has been initiated by a high-energy neutron bombarding a heavy nucleus such as uranium-235.

  • In fission, the bombardment of a large nucleus breaks it apart into smaller nuclei, releasing one or more types of radiation and a great amount of energy.

  • In fusion, small nuclei combine to form larger nuclei while great amounts of energy are released.

MA

Chapter 5: Nuclear Chemistry

5.1: Natural Radioactivity

  • An unstable nucleus is radioactive, which means that it spontaneously emits small particles of energy called radiation to become more stable.

  • Radioisotope: An isotope of an element that emits radiation.

  • Atomic Symbols: Written with the mass number in the upper left corner and the atomic number in the lower left corner.

  • Mass Number: The sum of the numbers of protons and neutrons in the nucleus.

  • Atomic Number: It is equal to the number of protons.

Types of Radiation

  • Alpha Particle: It has two protons and two neutrons.

    • It has a mass number of 4, an atomic number of 2, and a charge of 2+.

  • Beta Particle: It is a high-energy electron, has a charge of 1–, and it has a mass number of 0.

    • It is formed when a neutron in an unstable nucleus changes into a proton.

  • Positron: It has a positive charge with a mass number of 0.

    • It is produced by an unstable nucleus when a proton is transformed into a neutron and a positron.

    • Antimatter: A particle that is the opposite of another particle — an electron.

  • Gamma Rays: These are high-energy radiation, released when an unstable nucleus undergoes a rearrangement of its particle to give a more stable, lower-energy nucleus.


5.2: Nuclear Reactions

  • Radioactive Decay: A process where a nucleus spontaneously breaks down by emitting radiation.

  • Alpha Decay: An unstable nucleus may emit an alpha particle, which consists of two protons and two neutrons.

    • The mass number of the radioactive nucleus decreases by 4, and its atomic number decreases by 2.

    • Americium-241: Mostly found in smoke detectors used in homes and apartments, which undergoes alpha decay.

  • Beta Decay: The formation of beta particles results from the breakdown of a neutron into a proton and an electron.

    • The mass number of the radioactive nucleus and the mass number of the new nucleus is the same.

    • Radioactive Isotope Yttrium–90: A beta emitter, is used in cancer treatment and as a colloidal injection into large joints to relieve the pain of arthritis.

  • Positron Emission

    • A proton in an unstable nucleus is converted to a neutron and a positron.

    • The neutron remains in the nucleus, but the positron is emitted from the nucleus.

    • The mass number of the radioactive nucleus and the mass number of the new nucleus is the same.

    • The atomic number decreases by one, indicating a change in one element into one another.

  • Gamma Emission: Pure gamma emitters are rare, although gamma radiation accompanies most alpha and beta radiation.

  • Transmutation: A stable nucleus is bombarded by high-speed particles such as alpha particles, protons, neutrons, and small nuclei.


5.3: Radiation Measurements

  • When a radiology laboratory obtains a radioisotope, the activity of the sample is measured in terms of the number of nuclear disintegrations per second.

  • Curie (Ci): The original unit of activity.

    • It was defined as the number of disintegrations that occurs in 1 s for 1 g of radium, which is equal to 3.7 ✕ 10^10 disintegrations/s.

    • It was named after Marie Curie and her husband, Pierre, who discovered the radioactive elements; radium and polonium.

  • Becquerel (Bq): The SI unit of radiation activity, is 1 disintegration/s.

  • Radiation Absorbed Dose (Rad): A unit that measures the amount of radiation absorbed by a gram of a material such as body tissue.

  • Gray (Gy): The SI unit for absorbed dose.

    • The joules of energy absorbed by 1 kg of body tissue/

    • It is equal to 100 rad.

  • Radiation Equivalent in Humans (Rem): A unit that measures the biological effects of different kinds of radiation.

    • To determine the equivalent dose or rem dose, the absorbed dose (rad) is multiples by a factor that adjusts for biological damage caused by a particular form of radiation.

  • Sievert (Sv): The SI unit for the equivalent dose or biological damage.

    • One sievert is equal to 100 rem.

  • Lethal dose for one-half of the population: The amount of radiation to the whole body; the LD50.


5.4: Half-Life of a Radioisotope

  • Half-Life: The amount of time it takes for one-half of a sample to decay.

  • Decay Curve: A diagram of the decay of a radioactive isotope.

  • Phosphorous: A radioisotope used in the treatment of leukemia has a half-life of 14.3 days.

  • Radiological dating: A technique used by geologists, archaeologists, and historians to determine the age of ancient objects.

  • Carbon Dating (Carbon-14): The method for determining the age of an object containing organic material is by using the properties of radiocarbon, a radioactive isotope of carbon.


5.5: Medical Applications Using Radioactivity

  • Scanner: An apparatus used to produce an image of the organ.

    • The gamma rays emitted from the radioisotope in the organ can be used to expose a photographic plate, producing a scan of the organ.

  • Radioactive iodine uptake: The standard method of determining thyroid function.

  • Positron emission tomography (PET)

    • An imaging method where Positron emitters with short half-lives such as carbon-11, oxygen-15, nitrogen-13, and fluorine-18 are used.

    • Positron-Emitting Isotopes: These are used to study brain function, metabolism, and blood flow.

  • Computed Tomography (CT) Scan

    • Another imaging method is used to scan organs such as the brain, lungs, and heart.

    • A computer monitors the absorption of 30 000 X-ray beams directed at successive layers of the target organ.

    • This technique is successful in the identification of hemorrhages, tumors, and atrophy.

  • Magnetic resonance imaging (MRI)

    • A powerful imaging technique that does not involve X-ray radiation.

    • It is based on the absorption of energy when the protons in hydrogen atoms are excited by a strong magnetic field.

  • Brachytherapy

    • Also known as seed implantation.

    • It is an internal form of radiation therapy.

    • With internal radiation, a high dose of radiation is delivered to a cancerous area, while normal tissue sustains minimal damage.

Medical Applications of Radioisotopes

Isotope

Half-Life

Radiation

Medical Application

Au-198

2.7 days

Beta

Liver imaging; treatment of abdominal carcinoma

Ce-141

32.5 days

Beta

Gastrointestinal tract diagnosis; measuring blood flow to the heart

Cs-131

9.7 days

Gamma P

Prostate brachytherapy

F-18

110 min

Positron

Positron emission tomography (PET)

Ga-67

78 h

Gamma

Abdominal imaging; tumor detection

Ga-68

68 min

Gamma

Detection of pancreatic cancer

I-123

13.2 h

Gamma

Treatment of thyroid, brain, and prostate cancer

I-131

8.0 days

Beta

Treatment of Graves’ disease, goiter, hyperthyroidism, thyroid and prostate cancer

Ir-192

74 days

Gamma

Treatment of breast and prostate cancer

P-32

14.3 days

Beta

Treatment of leukemia, excess red blood cells, pancreatic cancer

Pd-103

17 days

Gamma

Prostate brachytherapy

Sr-85

65 days

Gamma

Detection of bone lesions; brain scans

Tc-99m

6.0 h

Gamma

Imaging of skeleton and heart muscle, brain, liver, heart, lungs, bone, spleen, kidney, and thyroid; most widely used radioisotope in nuclear medicine

Y-90

2.7 days

Beta

Treatment of liver cancer


5.6: Nuclear Fission and Fusion

  • Atomic Energy: The energy generated by splitting the atom.

  • During the 1930s, scientists bombarding uranium-235 with neutrons discovered that the U-235 nucleus splits into two smaller nuclei and produces a great amount of energy; which led to the discovery of — nuclear fission.

  • Chain Reaction: A fission reaction that will continue once it has been initiated by a high-energy neutron bombarding a heavy nucleus such as uranium-235.

  • In fission, the bombardment of a large nucleus breaks it apart into smaller nuclei, releasing one or more types of radiation and a great amount of energy.

  • In fusion, small nuclei combine to form larger nuclei while great amounts of energy are released.

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