8.2 Nuclear instability

• Nuclear instability occurs when a nucleus is prone to radioactive decay because of an imbalance in the proton-to-neutron ratio
• Too many neutrons in a nucleus may lead to beta-minus decay.
• Excessive nuclear energy in a nucleus often results in the emission of gamma rays to achieve stability.
• Stable nuclei have a balance between protons and neutrons.
• Stable nuclei have a balanced proton-to-neutron ratio.


  True
• Steps of beta-minus decay

  1️⃣ A neutron converts into a proton

  2️⃣ An electron is emitted

  3️⃣ An antineutrino is released
• Nuclei with lower binding energy per nucleon are more likely to be unstable
• Alpha decay reduces both the atomic and mass number of a nucleus.

  True
• Match the nuclear reaction type with its description:

  Fusion ↔️ Light nuclei combine

  Fission ↔️ Heavy nucleus splits

  Radioactive Decay ↔️ Unstable nucleus emits particles
• Radioactive decay involves unstable nuclei emitting particles or energy to become more stable.


  True
• What type of particle is emitted during the alpha decay of uranium-238?

  Alpha particle
• What is the formula relating the decay constant (λ) to the half-life (T½)?

  $\lambda =$$\frac{\ln(2)}{T_{\frac{1}{2}}}$
• What is the half-life of cobalt-60?

  5.27 years
• What formula is used to calculate the age of a sample using radioactive dating?

  N(t) = N_{0} \cdot e^{ - \lambda t}</latex>
• What are the two main nuclear forces governing nuclear stability?

  Strong and weak
• Which fundamental force overcomes the electrostatic repulsion between protons in the nucleus?

  Strong nuclear force
• Order the radioactive decay processes from most to least significant energy release:

  1️⃣ Alpha Decay

  2️⃣ Beta-Minus Decay

  3️⃣ Beta-Plus Decay

  4️⃣ Gamma Decay
• Beta-plus decay increases the atomic number of the nucleus.

  False
• In alpha decay, the atomic number decreases by 2
• What is the definition of half-life?

  Time for half decay
• What is the formula relating the decay constant (λ) to the half-life (T½)?

  $\lambda =$$\frac{\ln(2)}{T_{1 / 2}}$
• Match the radioactive dating technique with its corresponding isotope and half-life:

  Carbon-14 ↔️ ¹⁴C (5,730 years)

  Uranium-Lead ↔️ ²³⁸U (4.5 billion years)

  Potassium-Argon ↔️ ⁴⁰K (1.3 billion years)
• What type of shielding is required for gamma decay?

  Thick lead or concrete
• Which radioactive isotope is used in medical imaging to create images of the body?

  Technetium-99m
• Excessive nuclear energy in a nucleus often results in the emission of gamma rays to achieve stability.
• The strong nuclear force is the strongest of the four fundamental forces in nature


  True
• The strong nuclear force overcomes the electrostatic repulsion between protons.
• What is the nucleon ratio also known as?

  Proton-to-neutron ratio
• What happens to a nucleus when it deviates from the line of stability?

  Radioactive decay
• Gamma decay changes the atomic number of the nucleus.

  False
• What is the role of the strong nuclear force?

  Holds protons and neutrons together
• What is the process called when two light nuclei combine to form a heavier nucleus?

  Fusion
• In a nuclear reaction called fusion, two or more lighter nuclei combine to form a heavier nucleus
• What is the term for the process where one element changes into another due to nuclear reactions?

  Nuclear transmutation
• Classify the types of nuclear reactions based on their energy change from largest to smallest.

  1️⃣ Fusion

  2️⃣ Fission

  3️⃣ Radioactive decay
• After 10.54 years, 100g of cobalt-60 reduces to approximately 25g due to radioactive decay.
• Nuclear instability can occur due to an imbalance in the proton-to-neutron ratio or excessive nuclear energy.
• What is nuclear instability caused by?

  Imbalanced proton-to-neutron ratio
• The line of stability on a graph plots stable nuclei based on their proton and neutron numbers.


  True
• What type of particle is emitted during alpha decay?

  Helium nucleus