CHEM 410 CHAPTER 5

Types of nuclear reactions:

- Radioactive Decay - Nuclear Bombardment - Nuclear Fission - Nuclear Fussion

Iodine-131 has a half-life of 8.0 minutes. How many half-lives will pass in 120 minutes?

120 min×1 half-life/8.0 min=15 half-lives

One of the radioactive isotopes used in chemical and medical research is iodine-125, which has a half-life of 61 days. How long would it take for 0.25 g to remain of a 1.00 g sample of iodine-125?

122 days

Radioactive iodine-131 decays with a half-life of 8.0 days. A chemist obtains a fresh sample of iodine-131 and measures its radioactivity. She then determines that to do an experiment, the radioactivity cannot fall below 25% of the initial measured value. How long does she have to perform the experiment?

16.0 days

Ruthenium-106 has a half-life of 1.0 years. How many half-lives will pass in 25 years?

25 years×1 half-life/1.0 year= 25 half-lives

Which of the following represents the three main types of radiation ranked by increasing penetrating ability?

A) alpha < beta < gamma

Which of the following nuclei would be most likely to undergo β⁻ decay?

C-14

Which of these terms describes the following process? ²³⁹₉₄Pu → ²³⁵₉₂U + ⁴₂He²⁺ a) Chemical b) Fusion c) Exothermic

Exothermic

What type of nuclear process requires extremely high temperatures to occur?

Fusion

Which type of radiation has the greatest penetrating ability?

gamma ray

Which parent nuclide would give rise to the daughter nuclide Na-20 by positron emission?

Mg-20

The Cs-131 nuclide has a half-life of 30 years. After 120 years, 3.0 g remain. What is the original mass of the Cs-131 sample in grams?

N0×(1/2)4=3.0 gN0×(12)4=3.0 gN0=3.0 g×(2)^4=3.0 g×16=48 g Answer= 48g

What type of nuclei is used in PET scan instruments?

Positron emitters

An unstable isotope of Re-191 is a beta producer. What is the other product of the reaction?

Os-191

What type of medical imaging involves radioactivity as the imaging source?

PET scans

The nuclide Rn-204 is the daughter nuclide resulting from the α decay of what parent nuclide?

Ra-208

What nuclide is formed when Th-230 undergoes alpha emission?

Ra-226

What is ionizing radiation?

Radiation that can cause ionization processes to occur.

The stable nuclide ²⁰⁶₈₂Pb is formed from ²³⁸₉₂U by a long series of α and β⁻ decays. Which of the following nuclides could NOT be involved in this decay series?

Rn-222

Which of the following about fission and fusion is false?

The mass defect in a fission reaction is positive while the mass defect in a fusion reaction is negative.

The equation below is best described as ___________. ²³⁵₉₂U → ²³⁵₉₃Np + ⁰₋₁e a) Alpha Decay b) Beta Decay c) Gamma Emission d) Positron Emission

beta decay

The most likely decay mode (or modes) of the unstable nuclide ¹¹C would be

either positron production or electron capture or both.

The process that powers stars is

fusion

fission definition

the action of dividing or splitting something into two or more parts.

A significant difficulty in using fusion as an energy source is

the extreme conditions required to initiate and sustain fusion reactions.

Fusion definition

the process or result of joining two or more things together to form a single entity.

Complete the following nuclear decay process: ²³⁵₉₂U → ⁴₂He + ___

²³¹₉₀Th

What is the product of alpha emission from uranium-238?

²³⁴Th

Enriched uranium fuel used in fission reactors is that which contains a greater amount of

²³⁵U

What nuclide is formed when ²¹Na undergoes positron emission?

²¹Ne

²¹⁰Pb decays by emitting a β⁻ particle. What nuclide is produced?

²¹⁰Bi

What isotope is commonly used to determine thyroid activity and treat diseases of the thyroid?

¹³¹I

¹¹C is often used in PET (positron emission tomography) diagnostic equipment. What nuclide is produced in this decay process?

¹¹B

Which of the following has the greatest mass?

α particle

Electron capture transforms ⁴⁰₁₉K into what nuclide?

⁴⁰₁₈Ar

Which of the following symbols represents an alpha particle?

⁴₂He

Which of the following correctly depicts the nuclear reaction for chromium-51 decaying by electron capture?

⁵¹Cr + ⁰₋₁e → ⁵¹V

Based on nuclear stability, what is the symbol for the most likely product nuclide when Sr-80 undergoes decay?

⁸⁰₃₇Rb

Rubidium-87 is radioactive, decaying by the emission of a single beta particle. Write the nuclear equation for this decay.

⁸⁷Rb → ⁸⁷Sr + ⁰₋₁e

Complete the following nuclear bombardment equation by filling in the nuclear symbol for the missing species. ²³⁵₉₂U + ¹₀n → ? + ¹³⁹₅₄Xe + 3 ¹₀n

⁹⁴₃₈Sr