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Chapter 30. 0. Nuclear Physics. 30 Nuclear Physics. Slide 30-2. Slide 30-3. Slide 30-4. Slide 30-5. Reading Quiz. The mass number A of a nucleus is the number of ___________ in the nucleus. protons protons plus neutrons neutrons. Slide 30-6. Answer.

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Chapter 30

Chapter 30

0

Nuclear Physics


30Nuclear Physics

Slide 30-2





Reading Quiz

  • The mass number A of a nucleus is the number of ___________ in the nucleus.

    • protons

    • protons plus neutrons

    • neutrons

Slide 30-6


Answer

  • The mass number A of a nucleus is the number of ___________ in the nucleus.

    • protons

    • protons plus neutrons

    • neutrons

Slide 30-7


Reading Quiz

  • When a nucleus decays by giving off an electron, we call this ________ decay.

    • alpha

    • beta

    • gamma

Slide 30-8


Answer

  • When a nucleus decays by giving off an electron, we call this ________ decay.

    • alpha

    • beta

    • gamma

Slide 30-9


Reading Quiz

  • ________ decay results in a daughter nucleus that is the same as the parent nucleus.

    • Alpha

    • Beta

    • Gamma

Slide 30-10


Answer

  • ________ decay results in a daughter nucleus that is the same as the parent nucleus.

    • Alpha

    • Beta

    • Gamma

Slide 30-11


Nuclear Structure

Different isotopes of the same element have the same atomic number but different mass numbers.

Slide 30-12


Checking Understanding

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-13


Answer

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-14


Checking Understanding

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-15


Answer

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-16


Checking Understanding

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-17


Answer

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-18


Checking Understanding

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-19


Answer

  • How many neutrons are in the following isotope? (The isotope may be uncommon or unstable.)

    • 8

    • 7

    • 6

    • 5

    • 4

Slide 30-20


Boron, with atomic number Z=5, has two stable isotopes, with atomic mass numbers A=10 and A=11. Boron’s chemical atomic mass is 10.81. What are the approximate fractions of the two stable boron isotopes found in nature?

A. 92% 11B, 8% 10B

B. 80% 11B, 20% 10B

C. 50% 11B, 50% 10B

D. 20% 11B, 80% 10B

E. 8% 11B, 92% 10B

Checking Understanding

Slide 30-21


Boron, with atomic number Z=5, has two stable isotopes, with atomic mass numbers A=10 and A=11. Boron’s chemical atomic mass is 10.81. What are the approximate fractions of the two stable boron isotopes found in nature?

A. 92% 11B, 8% 10B

B. 80% 11B, 20% 10B

C. 50% 11B, 50% 10B

D. 20% 11B, 80% 10B

E. 8% 11B, 92% 10B

Answer

Slide 30-22


Magnesium has three stable isotopes, with the following natural abundances:

79% of naturally occurring magnesium is 24Mg, with u=23.99

10% of naturally occurring magnesium is 25Mg, with u=24.99

11% of naturally occurring magnesium is 26Mg, with u=25.98

What is the chemical atomic mass of magnesium?

Example Problem

Slide 30-23


Stability natural abundances:

Slide 30-24


Binding Energy natural abundances:

Slide 30-26


Binding Energy of a Helium Nucleus natural abundances:

Slide 30-27


There are several elements for which there is only one stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

All but 0.00013% of naturally occurring helium is the stable isotope 4He.

100% of naturally occurring niobium is the stable isotope 93Nb.

100% of naturally occurring bismuth is the stable isotope 209Bi.

What is the ratio of neutrons to protons for these three isotopes?

16O, with u=15.994915, is stable; 19O, with u=19.003577, is not. What is the binding energy per nucleon for each of these nuclei?

Example Problems

Slide 30-25


Curve of Binding Energy stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • Light nuclei can become more stable through fusion.

  • Heavy nuclei can become more stable through fission.

  • All nuclei larger than a certain size spontaneously fission.

Slide 30-28


Nuclear Forces stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-29


Nuclear Energy Levels and Decay stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • Different levels for neutrons and protons

  • Energy difference between levels is very large

  • Nuclei can become more stable through certain decay modes

Slide 30-30


Example Problem stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • The beryllium isotope 11Be decays to the boron isotope 11B.

    • Show the nucleons of both nuclei on the shell-model energy-level diagrams below.

    • Explain why this decay is energetically favorable.

Slide 30-31


Nuclear Radiation stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-32


Alpha Decay stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-33


Beta Decay stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-34


Checking Understanding stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the daughter nucleus for this decay:

  • 90Sr → ?X+e-

    • 90Y

    • 89Y

    • 90Rb

    • 89Rb

Slide 30-35


Answer stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the daughter nucleus for this decay:

  • 90Sr → ?X+e-

    • 90Y

    • 89Y

    • 90Rb

    • 89Rb

Slide 30-36


Checking Understanding stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the daughter nucleus for this decay:

  • 222Rn → ?X+α

    • 220Po

    • 218Po

    • 220Ra

    • 218Ra

Slide 30-37


Answer stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the daughter nucleus for this decay:

  • 222Rn → ?X+α

    • 220Po

    • 218Po

    • 220Ra

    • 218Ra

Slide 30-38


Checking Understanding stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the daughter nucleus for this decay:

  • 99Tc → ?X+γ

    • 99Tc

    • 99Mo

    • 99Nb

    • 99Ru

Slide 30-39


Answer stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the daughter nucleus for this decay:

  • 99Tc → ?X+γ

    • 99Tc

    • 99Mo

    • 99Nb

    • 99Ru

Slide 30-40


Example Problem stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

11Li is an unstable isotope of lithium. Sketch the energy level structure for the neutrons and the protons in this nucleus. What decay mode would you expect for this nucleus? Write the full equation for the decay you expect, including the daughter nucleus.

Slide 30-41


Decay Series stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • 235U is unstable

  • Through a series of alpha beta decay, settles on 207Pb

  • In a star, everything ends up as 56Fe

Slide 30-41


Fission stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-46


Operation of a Geiger Counter stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-42


Example Problem: Activity stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

0.693N

t1/2

______

R = rN =

Most of the internal radiation of the human body is due to a single isotope, the beta emitter 40K, with half life of 1.28×109 years. The body contains about 0.35% potassium by mass; of this potassium, about 0.012% is 40K. What is the total activity, in Bq, of a 70 kg human?

Slide 30-43


Half Life stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-44


Nuclear Decay stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-45


Example Problems: Decay Times stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

The Chernobyl nuclear reactor accident in the Soviet Union in 1986 released a large plume of radioactive isotopes into the atmosphere. Of particular health concern was the short-lived (half life: 8.0 days) isotope 131I, which, when ingested, is concentrated in and damages the thyroid gland. This isotope was deposited on plants that were eaten by cows, which then gave milk with dangerous levels of 131I. This milk couldn’t be used for drinking, but it could be used to make cheese, which can be stored until radiation levels have decreased. How long would a sample of cheese need to be stored until the number of radioactive atoms decreased to 3% of the initial value?

Slide 30-46


Example Problems: Decay Times stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

A scrap of parchment from the Dead Sea Scrolls was found to have a 14C/12C ratio that is 79.5% of the modern value. Determine the age of this parchment.

Slide 30-46


Dose and Dose Equivalent stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

1 Gy = 1.00 J/kg of absorbed energy

Dose equivalent in Sv = (dose in Gy) x RBE

Slide 30-47


Example Problems: Determining Dose stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

In a previous example, we computed the activity of the 40K in a typical person. Each 40K decay produces a 1.3 MeV beta particle. If 40% of the energy of these decays is absorbed by the body, what dose, and what dose equivalent, will a typical person receive in one year from the decay of these nuclei in the body?

Slide 30-48


Summary stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-50


Summary stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

Slide 30-51


Additional Questions stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the decay mode of the following decay?

  • 137Cs → 137Ba + ?

    • Alpha decay

    • Beta-minus decay

    • Beta-plus decay

    • Gamma decay

Slide 30-52


Answer stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the decay mode of the following decay?

  • 137Cs →137Ba + ?

    • Alpha decay

    • Beta-minus decay

    • Beta-plus decay

    • Gamma decay

Slide 30-53


Additional Questions stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the decay mode of the following decay?

  • 222Rn → 218Po + ?

    • Alpha decay

    • Beta-minus decay

    • Beta-plus decay

    • Gamma decay

Slide 30-54


Answer stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the decay mode of the following decay?

  • 222Rn →218Po + ?

    • Alpha decay

    • Beta-minus decay

    • Beta-plus decay

    • Gamma decay

Slide 30-55


Additional Questions stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the decay mode of the following decay?

  • 60Ni* → 60Ni + ?

    • Alpha decay

    • Beta-minus decay

    • Beta-plus decay

    • Gamma decay

Slide 30-56


Answer stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

  • What is the decay mode of the following decay?

  • 60Ni* →60Ni + ?

    • Alpha decay

    • Beta-minus decay

    • Beta-plus decay

    • Gamma decay

Slide 30-57


Additional Example Problem stable isotope, or for which one stable isotope dominates the natural abundance. Three examples are:

A 60 kg laboratory worker receives a whole-body

x-ray exposure of 0.50 mSv. The x-ray wavelength is 0.15 nm. How many x-ray photons are absorbed in the worker’s body? X rays have an RBE of 1.

Slide 30-58


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