Identify the two key factors that determine nuclear stability Factors determining nuclear stability Answer Bank pressure on the nucleus temperature of the nucleus physical state of the element ratio of neutrons t0 protons number of nucleons in the nucleus
The Correct Answer and Explanation is:
Correct Answer:
- Ratio of neutrons to protons
- Number of nucleons in the nucleus
Explanation
Nuclear stability refers to how likely a nucleus is to remain intact without undergoing radioactive decay. Two primary factors determine the stability of a nucleus: the neutron-to-proton ratio and the total number of nucleons (which includes both protons and neutrons).
1. Neutron-to-Proton Ratio (n/p ratio):
The balance between neutrons and protons plays a critical role in nuclear stability. Neutrons help to offset the electrostatic repulsion between the positively charged protons in the nucleus. If there are too few neutrons, the repulsion between protons may destabilize the nucleus. If there are too many neutrons, the excess energy in the system can also lead to instability. For light elements (like carbon or oxygen), a roughly 1:1 ratio of neutrons to protons ensures stability. For heavier elements, a higher ratio of neutrons is needed, often around 1.5:1. Nuclei that fall outside the optimal range tend to be unstable and undergo radioactive decay to reach a more stable state.
2. Number of Nucleons (Mass Number):
The total number of nucleons (protons plus neutrons) affects how forces within the nucleus behave. There is a range of mass numbers within which nuclei are stable. As the number of nucleons increases, the strong nuclear force must overcome the growing electrostatic repulsion between protons. When the nucleus becomes too large (as in elements beyond bismuth), it becomes inherently unstable, even with a high neutron-to-proton ratio. This is why all elements with atomic numbers greater than 83 are radioactive.
Factors like temperature, pressure, or physical state of the element do not significantly affect nuclear stability because nuclear forces operate at the subatomic level and are not influenced by external conditions in the same way as chemical bonds.
