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Homework: Nuclear Chemistry

See also Alpha and Beta Radiation
Positron Emission and Electron Capture

Answer the questions with complete sentences.

  1. What is radiation in general? Give examples of some types of radiation. Distinguish between ionizing radiation and non-ionizing radiation.
  2. What causes nuclear radiation?
  3. What are the three types of nuclear radiation and how are they different from one another?
  4. All kinds of radiation are not equally dangerous. Which kinds can cause physical harm to living things and which can’t? Why?
  5. For each of the following decay modes give the nuclear symbol of the emitted or absorbed particle and give a rule for how the decay changes the original nucleus.
    1. α alpha radiation:
    2. β beta radiation:
    3. β+ positron radiation:
    1. γ gamma radiation
    2. electron capture:
  6. For each of the following decay modes give an example of a balanced nuclear decay equation. Use other handouts you have received or the internet to find some examples.
    1. α alpha radiation:
    2. β beta radiation:
    3. β+ positron radiation:
    1. γ gamma radiation
    2. electron capture:

  1. What is a Geiger counter and how does it work?
  2. What kind of shielding is required for each of the three major types of ionizing radiation (alpha, beta-minus, and gamma)?
  3. Experts disagree but the general consensus is that no amount of exposure to ionizing radiation is safe. If there is an intense source nearby what is the best strategy: to shield yourself from it or to move away from it? Why?
  4. Define the term half-life. Also, describe how the intensity of radiation from a sample changes over time.
  1. How much of a sample of radioactive atoms remains undecayed for each of the following numbers of half-lives?
    1 half-life:                                                          4 half-lives:
    2 half-lives:                                                       3.25 half-lives:
    3 half-lives:
  2. If the half-life of an unstable isotope is 31 days then how long will it until be the following amounts remain undecayed?
    50%                                                          6.25%
    25%                                                          10.5%
  3. How many half-lives aluminum-26 have passed if the fraction remaining is 3.125%? How much time does it take for an original sample of this isotope to decay to this level? The half-life of 26Al is 717,000 years.
  4. For equal numbers of atoms, which type has higher-intensity radiation: a radioactive isotope with a short half-life or one with a long half-life. Why?
  5. Tritium has a half-life of 12.3 years. A sample of 10 milligrams has been left on a shelf for 20 years. What percentage of the original tritium sample remains undecayed? What mass of tritium is still around? (Hint: first find the number of half-lives and then find the fraction remaining).

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Nuclear Reactions

Complete the following exercises to practice writing and completing nuclear decay, fusion, fission, and transmutation equations.

For the following exercises, fill in the missing particle and give a name to what is happening. Identify whether it is a type of nuclear decay, fission, fusion, or transmutation. Only one particle is missing from each equation. Space has been provided both before and after the arrow but you must determine where the missing particles belong.

  1. 24797Bk                => 42He
  2. 20178Pt                => 0–1e
  3. 4930Zn                => 4929Cu
    (there are two possible correct answers; give both)
  4.                 => 7535Br + 0+1e+
  5.                 => 42He + 21884Po
  1.                 2814Si => 3116S + 10n0
  2.                 126C + 25098Cf => 410n0
  3.                 11H + 31H =>  
  4.                 10n0 => 9037Rb + 14355Cs + 310n0
  5.                 23994Pu + 10n0 => 14853Ce + 210n0

Each of the following exercises describes a nuclear change. Write a correct and balanced nuclear equation for each one.

  1. A Roentgenium-272 nucleus undergoes alpha-decay.
  2. Write an equation for the positron decay of zirconium-86.
  3. An iron-58 nucleus is hit by a bismuth-209 nucleus to form meitnerium-266 and a neutron.
  1. Write an equation for the electron capture decay of tungsten-180.
  2. A plutonium-239 nucleus absorbs a neutron and fissions to release three neutrons, a krypton-81 nucleus and one other atomic nucleus.
  3. Nitrogen-14 is the result of the beta-decay another isotope of another element. Identify the element and write the nuclear equation.

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The type of reaction will be indicated by the following codes: α (alpha radiation), β (beta-minus radiation), β+ (positron radiation), or EC (electron capture). Complete each nuclear equation.
  1. β13  5B  —>
  2. α 23492U —>         +
  3. EC 8642Mo +         —>
  4. β+        —> 50 28Ni +
  5. α         —> 22687Fr +
  6. β        —> 87 38Sr +
  7. β+11757La  —>
  8. EC         +         —> 18978Pt
  1. α         —> 18676Os +
  2. β+5731Ga  —>
  3. β        —> 40 17Cl +
  4. EC         +         —> 12456Ba
  5. α 24195Am —>         +
  6. β3919K  —>
  7. β+        —> 67 34Se +
  8. EC 12860Nd +         —>
Last updated: Feb 25, 2015        Home