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Ch.20 - Radioactivity and Nuclear Chemistry
Chapter 20, Problem 37

Determine whether or not each nuclide is likely to be stable. State your reasons. a. Mg-26 b. Ne-25 c. Co-51

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Identify the atomic number and mass number of the nuclide. For Co-51, cobalt (Co) has an atomic number of 27, and the mass number is 51.
Calculate the number of neutrons by subtracting the atomic number from the mass number: Neutrons = Mass number - Atomic number = 51 - 27.
Check the neutron-to-proton (n/p) ratio. A stable n/p ratio is typically around 1 for lighter elements and increases slightly for heavier elements.
Compare the n/p ratio of Co-51 to the known stable isotopes of cobalt. The most stable isotope of cobalt is Co-59, which has a different n/p ratio.
Consider the position of Co-51 on the chart of nuclides. Nuclides far from the line of stability are usually unstable and may undergo radioactive decay.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nuclear Stability

Nuclear stability refers to the ability of a nucleus to remain intact without undergoing radioactive decay. Stable nuclides have a balanced ratio of protons to neutrons, which helps to counteract the repulsive forces between protons. Generally, nuclides with a neutron-to-proton ratio close to 1:1 are more likely to be stable, while those with extreme ratios tend to be unstable and radioactive.
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Isotopes and Their Stability

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons. The stability of an isotope can vary significantly; for example, some isotopes are stable while others are radioactive and decay over time. Understanding the specific isotopes of an element, such as Co-51, is crucial for predicting their stability and behavior in nuclear reactions.
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Magic Numbers in Nuclear Physics

Magic numbers are specific numbers of nucleons (protons or neutrons) that result in particularly stable configurations of the nucleus. These numbers correspond to complete shells of nucleons, leading to enhanced stability. For example, nuclei with 2, 8, 20, 28, 50, 82, or 126 nucleons are often more stable, while those that do not align with these magic numbers may be more prone to instability and decay.
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