chapter 13. copyright © houghton mifflin company. all rights reserved. 6 | 3 chapter learning...

Chapter 13

Copyright © Houghton Mifflin Company. All rights reserved. 6 | 3

Chapter Learning Objectives

By the end of the chapter, you will recognize that

a. Nuclear reactions result from instability of the nucleus.

b. Certain combinations of nucleons are inherently unstable, causing some nuclides to undergo radioactive decay.

c. Types of radioactive decay include alpha emission, beta emission, and gamma emission.


Chapter Learning Objectives (cont)

d. Each radioisotope has a characteristic half-life,the time it takes for half the sample to undergo radioactive decay.

e. Radioactive dating uses the amount of a radioisotope remaining in a sample to determine its age.

f. Radioisotopes in the environment contribute to the public’s unavoidable exposure to radiation.

g. Matter lost during nuclear transformations undergoes conversion to energy.


X-rays, the Forerunner to Radioactivity

X-rays are high source of pure energy form of electromagneticradiation

Figure 6.4: X ray imageof Bertha Röntgen's hand

Credit: Corbis


Chapter Outline

• Nuclear vs. Chemical Reactions a. Radioisotopes

1. Atoms that have unstable nuclei are radioactive, meaning that the nucleus may release energy and/or particles to become more stable.

b. Formation of New Elements1. Unlike in chemical reactions, new elements can be

formed during nuclear reactions called transmutation.

Mass number = # protons + # neutrons

Isotopes are atoms that have different numbers of neutrons but the sameNumber of protons.

Figure 6.2: Atom smashing is like a pool break

Credit: Getty Images

Figure 6.7: Pierre and Marie Curie

Credit: Corbis

Search for newRadioactive elementsPolonium and Radium


Chapter Outline

• Types of Nuclear Decay:

Alpha, Beta, and Gamma Emissionsa. Alpha-Particle Emission

1. An alpha particle is identical to a helium-4 nucleus (two protons and two neutrons)

2. Alpha-particle emission results in a decrease in the atomic number by two and a decrease in the mass number by four.


Alpha-Particle Emission

Example A: 226Ra 4He + ?88 2

226Ra 4He + 222Rn88 2 86

Example B: 240Pu 4He + ?94 2

240Pu 4He + 236U94 2 92


Chapter Outline

• Types of Nuclear Decay (cont)b. Beta-Particle Emission

1. A beta particle is identical to an electron.

2. Results from the conversion of a neutron to a proton and a beta particle

3. The atomic number increases by one, and the mass number remains the same.


Beta-Particle Emission

= electron

Example A: 228Ra 0 + ?88 -1

228Ra 0 + 228Ra-188 89

Example B: 214Pb 0 + ?82 -1

214Ra 0 + 214Bi-182 83


Chapter Outline

• Types of Nuclear Decay

a. Gamma-Ray Emission

1. Gamma rays are high-energy electromagnetic radiation only.

2. There is no change in the identity of an element upon the release of gamma rays.


Gamma-Ray Emission

Example A: 222Ram 0 + ?83 0

222Ram 0 + 222Ra 083 83

m stands for metastable


Chapter Outline

• Artificial Transmutation a. Induced Radioactivity

1. Bombarding a normally stable nucleus with high-energy particles can lead to transmutation of one element into another.

b. Transuranic Elements1. Elements heavier than uranium (Z=92), the

transuranic elements, do not occur in nature but can be made through artificial transmutation.

Figure 6.11: Irène and Frédéric Joliot-Curie

Credit: Corbis

Were the 1st to produce a radioactive nuclide through artificial transmutation


Figure 6.12:Transuranicelements in the periodic table

Elements higher than Uranium 92are transuranic elements


Chapter Outline

• Radioactive Decaya. Half-Life

1. The time required for half a sample to undergo radioactive decay


Half-Life

Figure 6.15: A Geiger-Müller counter

Figure 6.20: Geiger-Müller counterwith radioactive antique orange plate


Chapter Outline

• Radioactive Decay (cont)b. Radioactive Dating

1. The radioactive decay of carbon-14 can be used to estimate the age of organic materials.

6C126C13

6C14

Types of Carbon Isotopes

Mass number = # protons + # neutrons


The process of Carbon-14 Dating


Figure 6.17: The Shroud of Turin

Credit: The Image Works

Reputed as the burial cloth of Jesus Christ. C-14 dating by 3 independent labs report theCloth originated during the Medieval times, Between A.D. 1260-1390.


Figure 6.18: Mummified remainsfound frozen in the Italian Alps

Credit: Landov

At least 5000 years oldBy carbon-14 dating


Chapter Outline

• Radiation Exposurea. Background Exposure

1. Consumer and natural sources such as cosmic rays and radon

b. Biological Effects of Radiation1. Ionizing radiation can lead to damage in both body

cells (somatic damage) and reproductive cells (genetic damage).

2. The penetrating power of the types of radiation follows the general trend:

gamma rays > beta particles > alpha particles


Figure 6.21: Sources of radiation


Figure 6.22: Means and result of radon exposure


Relative Penetration of Radiation


Chapter Outline

• Energy of the Nucleusa. Mass-to-Energy Conversion

1. Mass can be converted to energy during nuclear reactions.

2. E = mc2.

b. Binding Energy of a nucleus is1. The mass of a nucleus is always less than the sum of the masses of its

constituent nucleons.

2. This mass defect was converted to the “binding energy”, the energy required to dissociate an atom into separate neutrons, protons, and electrons

3. The energy emitted when separate neutrons, protons, and electrons combine to form an atom.

4. Equivalent to a quantity of mass express by Einstein’s equation, E=mc2


Such as the study of the chemical effects resulting from the absorption of radiation within living animals, plants, and other materials. The radiation chemistry controls much of radiation biology as radiation has an effect on living things at the molecular scale, to explain it another way the radiation alters the biochemicals within an organism, the alteration of the biomolecules then changes the chemistry which occurs within the organism, this change in biochemistry then can lead to a biological outcome. As a result nuclear chemistry greatly assists the understanding of medical treatments (such as cancer radiotherapy) and has enabled these treatments to improve.

Applications of Nuclear Chemistry


Radiation therapy (or radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to control malignant cells (not to be confused with radiology, the use of radiation in medical imaging and diagnosis). Radiotherapy may be used for curative or adjuvant cancer treatment. It is used as palliative treatment (where cure is not possible and the aim is for local disease control or symptomatic relief) or as therapeutic treatment (where the therapy has survival benefit but is not curative). Total body irradiation (TBI) is a radiotherapy technique used to prepare the body to receive a bone marrow transplant. Radiotherapy has a few applications in non-malignant conditions, such as the treatment of trigeminal neuralgia, severe thyroid eye disease, pterygium, prevention of keloid scar growth, and prevention of heterotopic ossification. The use of radiotherapy in non-malignant conditions is limited partly by worries about the risk of radiation-induced cancers.

Varian Clinac 2100C Linear Accelerator

http://en.wikipedia.org/wiki/Medicine

http://en.wikipedia.org/wiki/Ionizing_radiation

http://en.wikipedia.org/wiki/Cancer

http://en.wikipedia.org/wiki/Oncology

http://en.wikipedia.org/wiki/Malignant

http://en.wikipedia.org/wiki/Cell_%28biology%29

http://en.wikipedia.org/wiki/Radiology

http://en.wikipedia.org/wiki/Medical_imaging

http://en.wikipedia.org/wiki/Diagnosis

http://en.wikipedia.org/w/index.php?title=Curative&action=edit

http://en.wikipedia.org/wiki/Adjuvant

http://en.wikipedia.org/wiki/Palliative_treatment

http://en.wikipedia.org/wiki/Total_body_irradiation


iodine-131 radioactiveDye injected into aHuman body

Alternative energy sources using nuclear energy, such as nuclear power plantsand reactors.


Chapter Outline

• Energy of the Nucleus (cont)

c. Fission1. Following splitting (fission) of the uranium-235

nucleus, the masses of the products are less than the masses of the reactants.

2. The “missing mass” is released as energy.

d. The Manhattan Project1. The Manhattan Project was the code name for the

effort to develop a fission-based atomic bomb during World War II.


Figure 6.26: A neutron bombardinga heavy nucleus begins fission

Fission event is within an atom bomb isinitiated by a neutron (gray) bombardinga heavy nucleus such as uranium.

The nucleus breaksInto smaller pieces, releasing a lot of energy


4 Major Research Teams involved in the Manhattan Project

The existing Metallurgical Laboratory at the University of Chicago ,charged with the creation of a sustained nuclear fission chain reaction.A new laboratory near Knoxville, Tennessee (now known as the Oak Ridge National Laboratory), charged with the enrichment of U-235A new laboratory in Hanford, Washington, charged with the production, isolation and purification of Pu-239A new laboratory in Los Alamos, New Mexico, directed by J. Robert Oppenheimer, charged with the design and construction of the atomic bomb.

Figure 6.1: The now-familiarmushroom cloud of the Trinity test

Credit: Corbis


“Little Boy” dropped on Hiroshima, Japan

August 6th, 1945

“Fat Man” dropped on Nagasaki, Japan

August 9th, 1945


Hiroshima before (top) and after (bottom)Nagasaki before (top) and after (bottom)


Figure 6.27: Fusion: small nucleiform larger nuclide, release energy

This type of Fusion is beingExamined asAn alternativeEnergy sourceOn Earth.

Small nuclei come together to form larger nuclide, releasing energy


Key Words

• Nucleons• Radioactive decay• Nuclide• Radioisotope• Transuranic elements• X rays• Free radical• Alpha () particles• Beta () particles• Gamma () rays• Transmutation

• Positron• Half-life• Geiger-Müller

counter• Radioactive dating• Somatic damage• Genetic damage• Strong nuclear force• Fission• Fusion• Mass defect• Binding energy

chapter 13. copyright © houghton mifflin company. all rights reserved. 6 | 3 chapter learning...

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betaparticle emission

beta emission

alpha emission

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beta particle

alpha particle

nuclear reactions