Textbook Question
Predict the type of radioactive decay process for the following radionuclides: (c) phosphorus-32. (d) chlorine-39.
Ch.21 - Nuclear Chemistry
Chapter 21, Problem 21
One of the nuclides in each of the following pairs is radioactive. Predict which is radioactive and which is stable: (a) 39₁₉K and 40₁₉K. (b) ²⁰⁹Bi and ²⁰⁸Bi. (c) nickel-58 and nickel-65.
Verified step by step guidance1
Step 1: Understand the concept of nuclear stability. Generally, nuclides with a balanced ratio of protons to neutrons are stable. Nuclides with too many or too few neutrons compared to protons tend to be radioactive.
Step 2: Analyze the isotopes in pair (a) 39₁₉K and 40₁₉K. Calculate the neutron number for each isotope by subtracting the atomic number (19) from the mass number (39 and 40, respectively). Compare the neutron-to-proton ratio to determine stability.
Step 3: Examine the isotopes in pair (b) ²⁰⁹Bi and ²⁰⁸Bi. Note that bismuth (Bi) is known for having a stable isotope, ²⁰⁹Bi, which is the heaviest stable isotope. Consider the stability of ²⁰⁸Bi in comparison.
Step 4: Evaluate the isotopes in pair (c) nickel-58 and nickel-65. Calculate the neutron number for each isotope by subtracting the atomic number of nickel (28) from the mass numbers (58 and 65, respectively). Compare the neutron-to-proton ratios to assess stability.
Step 5: Use the concept of the 'band of stability' to predict which isotopes are stable. Isotopes that fall within this band are generally stable, while those outside it are likely radioactive. Consider the neutron-to-proton ratios calculated in previous steps to make predictions for each pair.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Radioactive Decay
Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. This can occur in various forms, including alpha, beta, and gamma decay. The stability of a nuclide is determined by its neutron-to-proton ratio; those with an imbalance are more likely to be radioactive.
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03:00
Rate of Radioactive Decay
Nuclide Stability
Nuclide stability refers to the likelihood of a nuclide to remain unchanged over time. Stable nuclides have a balanced ratio of protons and neutrons, while unstable ones tend to undergo radioactive decay. Understanding the stability of nuclides is essential for predicting which isotopes are radioactive.
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03:13Intepreting the Band of Stability
Isotopes
Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This difference in neutron count can affect the stability of the isotope, leading to some isotopes being stable while others are radioactive. Identifying isotopes is crucial for determining their radioactive properties.
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Related Practice
Textbook Question
Each of the following nuclei undergoes either beta decay or positron emission. Predict the type of emission for each: (a) tritium, 31H.
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Textbook Question
Each of the following nuclei undergoes either beta decay or positron emission. Predict the type of emission for each: b. 9938Sr
Textbook Question
Despite the similarities in the chemical reactivity of elements in the lanthanide series, their abundances in Earth's crust vary by two orders of magnitude. This graph shows the relative abundance as a function of atomic number. Which of the following statements best explains the sawtooth variation across the series? (a) The elements with an odd atomic number lie above the belt of stability. (b) The elements with an odd atomic number lie below the belt of stability. (c) The elements with an even atomic number have a magic number of protons. (d) Pairs of protons have a special stability.
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