In the context of radioactive decay, the nucleus least likely to undergo radioactive decay would be the nucleus with a stable configuration. This means that the nucleus is already in a state where it does not need to undergo any changes to reach a more stable form. Here are a few examples to illustrate this:
1. Noble Gas Nuclei: Nuclei of noble gases such as Helium (He), Neon (Ne), or Argon (Ar) are considered stable due to their complete outer electron shells. These nuclei are less likely to undergo radioactive decay compared to nuclei of other elements that are seeking stability through decay.
2. Common Stable Isotopes: Some isotopes of elements, like Carbon-12 (12C) and Oxygen-16 (16O), have a stable configuration with a balanced number of protons and neutrons. These stable isotopes are less likely to undergo radioactive decay.
3. Magic Numbers: Nuclei with a "magic number" of protons or neutrons (2, 8, 20, 28, 50, 82, 126) tend to be more stable and less likely to undergo radioactive decay. For example, nuclei with 2, 8, or 20 protons/neutrons exhibit increased stability.
Overall, nuclei that already possess stability through a balanced number of protons and neutrons, complete electron shells, or magic numbers are less likely to undergo radioactive decay.
