Nuclear Chemistry

Chapter 4: Discovering the Secrets of the Nucleus

From a Photographic Mystery to the Atomic Bomb

Chapter 5: Harnessing the Secrets of the Nucleus www.grossmont.edu/.../powerpoint%20lectures/ch%204& ...

Nuclear Energy, Nuclear Medicine, and a Nuclear Calendar

TEKS

• 12 (A) describe the characteristics of alpha, beta, and gamma radiation;

• 12 (B) describe radioactive decay process in terms of balanced nuclear equations; and

• 12 (C) compare fission and fusion reactions.

Figure 4.1

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Antoine Henri Becquierel.

© 2003 John Wiley and Sons Publishers

Courtesy Culver Pictures, Inc.

Radioactive Decay

• Discovered by Antoine Henri Becquerel in 1896– He saw that photographic plates developed

bright spots when exposed to uranium metals

Types of nuclear reactions

• Radioactive Decay – nucleus decays spontaneously giving off an energetic particle

• Nuclear Bombardment – shoot a high energy particle at the nucleus of another atom and watch what happens

Writing Nuclear Equations

Figure 4.4: The components of α rays, β rays, and γ rays.

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Figure 4.2: The penetrating power of radiation.

© 2003 John Wiley and Sons Publishers

Figure 5.3: Ionizing power and penetrating power: an analogy.

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Types of radioactive decay• alpha particle emission • beta emission • positron emission• electron capture• gamma emission

Types of radioactive decay

• alpha particle emission– loss of a helium

nucleus.

• Problem Pu-239 (plutonium 239) loses an alpha particle (He nucleus). Write the nuclear reaction

Types of radioactive decay

• beta emission – A neutron splits into a proton and

electron which is spit out as a particle.

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11

10

particle emission

Types of radioactive decay• positron emission

– A proton kicks out positive charge (a positron, +) to become a neutron.

– The positron collides with an electron annihilating both and generating energy

Types of radioactive decay• electron capture (EC)

–an electron (from inner shell) is sucked into the nucleus to combine with a proton – produces a neutron.

• gamma emission –emission of energy (photon) from

an unstable nucleus.

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01

11

00

9943

9943 TcTc

metastable

m

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How does an atom’s atomic number change when its nucleus loses a(n): (a) α particle, (b) β particle, (c) ray? How does that atom’s mass number change with the loss of each of these?

QUESTION

• Pu-239 (plutonium 239) loses an alpha particle (He nucleus). Write the nuclear reaction.

Nuclear Bombardment Reactions

• Transmutation – changing one element to another by shooting a nuclear particle at its nucleus.

• All transuranium elements (more than 92 protons) were created synthetically in particle accelerators.

Transmutation Reaction

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Figure 4.8: A typical fission reaction of U-235.

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Remains of a building after the explosion of the uranium bomb at Hiroshima, August 6, 1945.

© 2003 John Wiley and Sons Publishers

Courtesy Shigeo Hayashi

Figure 5.1: Schematic diagram of a nuclear power plant.

© 2003 John Wiley and Sons Publishers