General orrganic and biological chemistry structures off liffe 5th CH5 natural radioactivity GOB structures 5th ed

Lecture Presentation Chapter Nuclear Chemistry Karen C Timberlake General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter Nuclear Chemistry A nuclear medicine technologist works in a hospital where nuclear medicine is used to diagnose and treat a variety of medical conditions The technologist prepares the radioisotopes given to patients and uses a scanner that converts the radiation from various parts of the body into images General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter Readiness Key Math Skills • Using Positive and Negative Numbers in Calculations (1.4B) • Solving Equations (1.4D) • Interpreting a Graph (1.4E) Core Chemistry Skills • Using Conversion Factors (2.6) • Counting Protons and Neutrons (4.4) • Writing Atomic Symbols for Isotopes (4.5) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 5.1 Natural Radioactivity In a nuclear pharmacy, a person working with radioisotopes wears protective clothing and gloves and uses a lead glass shield on a syringe Learning Goal Describe alpha, beta, positron, and gamma radiation General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Natural Radioactivity Radioactivity comes from unstable nuclei, which are • found in elements with atomic numbers 20 and higher • defined as nuclei in which the nuclear forces cannot offset the repulsions between the protons • radioactive, emitting small particles of energy called radiation to become more stable Radiation may take the form of alpha (α) and beta (β) particles, positrons (β+), or pure energy such as gamma (γ) rays General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Radioisotope A radioisotope • is an isotope of an element that emits radiation • can be one or more isotopes of an element • includes the mass number in its name The atomic symbol for iodine-131, a radioisotope used in the diagnosis and treatment of thyroid disorders, has a mass number of 131 and an atomic number of 53 General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Stable and Radioactive Isotopes General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Types of Radiation Radioisotopes emit radiation such as • alpha (α) particles, identical to a helium nucleus, • beta (β) particles, high energy electrons, • positrons (β+), • pure energy called gamma (γ) rays, General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Some Forms of Radiation General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Identify and write the symbol for each of the following types of radiation A alpha particle B positron C beta particle General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 5.5 Medical Applications Using Radioactivity (a) A scanner is used to detect radiation from a radioisotope that has accumulated in an organ (b) A scan of the thyroid shows the accumulation of radioactive iodine-131 in the thyroid Learning Goal Describe the use of radioisotopes in medicine General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Medical Applications Radioisotopes with short half-lives are used in nuclear medicine because • the cells in the body not differentiate between nonradioactive atoms and radioactive atoms • once incorporated into cells, the radioactive atoms are detected because they emit radiation, giving an image of an organ General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Radioisotopes, Medical Applications General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Scans with Radioisotopes After a radioisotope is ingested by the patient, • the scanner moves slowly over the organ where the radioisotope is absorbed • the radiologist determines the level and location of the radioactivity emitted by the radioisotope • the gamma rays emitted from the radioisotope can be used to expose a photographic plate, producing a scan of the organ General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Scans with Radioisotopes • A scan shows the radioactive isotope I-131 in the thyroid General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Positron Emission Tomography (PET) Positron emitters with short half-lives • can be used to study brain function, metabolism, and blood flow • might be carbon-11, oxygen-15, nitrogen-13, or fluorine-18 18 18 F  O  1e • combine with electrons after emission to produce gamma rays, which are then detected by computers, creating a 3-D image of the organ General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Positron Emission Tomography (PET) These PET scans of the brain show a normal brain on the left and a brain affected by Alzheimer’s disease on the right General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Computed Tomography (CT) • Another imaging method used to scan organs such as the brain, lungs, and heart is called computed tomography (CT) • A computer monitors the absorption of 30 000 X-ray beams directed at the brain in successive layers Differences in absorption based on tissue densities and fluids provide images of the brain A CT scan shows a tumor (yellow) in the brain General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Magnetic Resonance Imaging (MRI) Magnetic resonance imaging • is an imaging technique that does not involve X-ray radiation • is the least invasive imaging method available • is based on the absorption of energy when protons in hydrogen atoms are excited by a strong magnetic field • works because the energy absorbed is converted to color images of the body General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Magnetic Resonance Imaging (MRI) An MRI scan provides images of the heart and lungs General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Which of the following radioisotopes are most likely to be used in nuclear medicine? A 40K half-life 1.3 × 109 years B 42 K half-life 12 hours C 131 I half-life days General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Which of the following radioisotopes are most likely to be used in nuclear medicine? Radioisotopes with short half-lives are used in nuclear medicine A 40 K half-life 1.3  109 years B 42 K half-life 12 hours C 131 I half-life days General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake Not likely; half-life is too long Short half-life; likely used Short half-life; likely used © 2016 Pearson Education, Inc Chemistry Link to Health: Brachytherapy The process of brachytherapy, or seed implantation, is an internal from of radiation therapy Permanent brachytherapy • is a treatment option for prostate cancer in males • involves the implantation of 40 or more titanium capsules or “seeds” in the malignant area • utilizes radioactive iodine-125, palladium-103, or cesium-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 with minimal damage to adjacent normal cells General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Brachytherapy Temporary brachytherapy • is also a treatment option for prostate cancer in males • 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 and may be repeated in a few days The needles are removed after to 10 minutes depending on the activity of the iridium isotope General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc ... rays, General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Some Forms of Radiation General, Organic, and Biological Chemistry: Structures. .. source General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Properties of Radiation General, Organic, and Biological Chemistry: Structures. .. protective clothing and gloves and uses a lead glass shield on a syringe Learning Goal Describe alpha, beta, positron, and gamma radiation General, Organic, and Biological Chemistry: Structures of