2.2 Stable and unstable nuclei

• What are stable nuclei?

  Do not decay spontaneously
• Stable nuclei emit alpha, beta, or gamma particles during decay.

  False
• Neutrons have a charge of neutral
• What does the strong nuclear force bind together in the nucleus?

  Protons and neutrons
• The weak nuclear force is weaker than gravity.

  False
• Isotopes have the same number of protons but different numbers of neutrons.
• The neutron number is calculated as the difference between the mass number and the atomic number.
• Unstable nuclei decay through processes like alpha, beta, and gamma emission.
• Protons are located in the nucleus and have a positive charge.
• The number of electrons in an atom is equal to the number of protons.
• Order the forces by strength from strongest to weakest:

  1️⃣ Strong nuclear force

  2️⃣ Weak nuclear force

  3️⃣ Electromagnetic force

  4️⃣ Gravity
• Match the atomic attribute with its definition:

  Atomic Number (Z) ↔️ Number of protons in the nucleus

  Mass Number (A) ↔️ Total protons and neutrons in the nucleus

  Neutron Number (N) ↔️ Number of neutrons in the nucleus
• Gamma rays have low ionizing power but high penetration.
• Gamma decay involves emitting high-energy photons
• The radioactive decay curve follows an exponential decay pattern.


  True
• Stable nuclei do not spontaneously decay.

  True
• Electrons are negatively charged particles that orbit the nucleus in specific energy levels.


  True
• The strong nuclear force is the strongest force in the nucleus, but it has a short range of approximately 1 femtometer.


  True
• The weak nuclear force is weaker than the strong force but stronger than gravity.


  True
• Isotopes can be represented using both symbol notation and name format.


  True
• The mass number (A) represents the total number of protons and neutrons in the nucleus.
• The mass number (A) represents the total number of protons and neutrons in the nucleus.
• How do isotopes of the same element differ from each other?

  Number of neutrons
• How is the neutron number (N) calculated?

  N = A - Z
• For lighter elements, a neutron-to-proton ratio close to 1 typically results in greater nuclear stability.


  True
• Match the properties of stable and unstable nuclei:

  Stable Nuclei ↔️ Balanced neutron-to-proton ratio

  Unstable Nuclei ↔️ Imbalanced neutron-to-proton ratio
• What is radioactive decay?

  Unstable nuclei transform
• Alpha decay results in a significant decrease in both mass and charge.

  True
• Half-life is the time it takes for half of the radioactive atoms in a sample to decay.
• Steps to analyze the decay of a radioactive isotope with a half-life of 5 years

  1️⃣ After 5 years, half the atoms have decayed

  2️⃣ After 10 years, a quarter of the atoms remain

  3️⃣ Predict the remaining radioactivity over time
• Match the application of radioactive decay with its description:

  Radioactive Dating ↔️ Measures age of samples

  Nuclear Medicine ↔️ Medical imaging and treatment

  Nuclear Power ↔️ Generates electricity
• Unstable nuclei decay to become more stable
• Match the feature with the correct type of nuclei:

  Highly stable ↔️ Stable nuclei

  Decays spontaneously ↔️ Unstable nuclei
• Where are protons located in an atom?

  In the nucleus
• The number of protons in an atom determines its electrical neutrality.


  True
• The weak nuclear force is responsible for beta decay.
• Isotopes of the same element have the same chemical properties.


  True
• How is Carbon-12 represented in symbol notation?

  $_{6}^{12} \text{C}$
• Stable nuclei do not spontaneously decay or transform into other nuclei.


  True
• What are the three fundamental particles of an atom?

  Protons, neutrons, electrons