1 natural radioactivity gob structures

General, Organic, and Biological Chemistry: Structures of Life, 5/eKaren C. Timberlake

© 2016 Pearson Education, Inc.

Karen C. Timberlake

Lecture Presentation

Chapter 5

NuclearChemistry



Chapter 5 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.



Chapter 5 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)



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.



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.



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.



Stable and Radioactive Isotopes



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, .



Some Forms of Radiation



Study Check

Identify and write the symbol for each of the following types of radiation.A. alpha particleB. positronC. beta particle



Solution

Identify and write the symbol for each of the following types of radiation.A. alpha particle B. positron C. beta particle



Biological Effects of Radiation

Ionizing radiation strikes molecules in its path and • knocks away the electrons in

molecules, forming unstable ions such as H2O+.

• causes undesirable chemical reactions.

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

Different types of radiation penetrate the body to different depths.



Radiation Protection

Radiation protection requires • paper and clothing for blocking alpha particles.• a lab coat or gloves for blocking beta particles.• dense shielding such as lead or concrete to block

gamma rays.

For those working in an environment where radioactive materials are present, limit your exposure by• minimizing the amount of time spent near a radioactive

source.• increasing the distance from the source.



Properties of Radiation



Study Check

Indicate the type of radiation (alpha, beta, and/or gamma) protection for each type of shielding.A. heavy clothingB. paperC. leadD. thick concrete



Solution

Indicate the type of radiation (alpha, beta, and/or gamma) protection for each type of shielding.A. heavy clothing alpha, betaB. paper alphaC. lead alpha, beta, gammaD. thick concrete alpha, beta, gamma

1 natural radioactivity gob structures

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