Podcast
Questions and Answers
What does the mass defect represent in the context of nuclear physics?
What does the mass defect represent in the context of nuclear physics?
- The mass of neutrinos emitted during beta decay.
- The increase in mass due to relativistic effects.
- The mass of electrons lost during ionization.
- The difference between the mass of a nucleus and the combined mass of its individual nucleons. (correct)
Binding energy is the energy released when a nucleus is broken apart into its individual components.
Binding energy is the energy released when a nucleus is broken apart into its individual components.
False (B)
What happens to the stability of atomic nuclei as binding energy per nucleon increases?
What happens to the stability of atomic nuclei as binding energy per nucleon increases?
The stability increases.
In nuclear physics, the process where smaller nuclei combine to form a larger nucleus is called ______.
In nuclear physics, the process where smaller nuclei combine to form a larger nucleus is called ______.
Match each term with its correct definition:
Match each term with its correct definition:
What is the significance of a positive value for $\Delta m$ in a nuclear reaction?
What is the significance of a positive value for $\Delta m$ in a nuclear reaction?
Alpha particles are more penetrating than beta particles.
Alpha particles are more penetrating than beta particles.
What characterizes a 'random' process in the context of radioactive decay?
What characterizes a 'random' process in the context of radioactive decay?
Radioactive decay is considered spontaneous because its rate is not influenced by ______ factors.
Radioactive decay is considered spontaneous because its rate is not influenced by ______ factors.
Which of the following equations correctly represents the relationship between activity (A), decay constant ($\lambda$), and the number of radioactive nuclei (N)?
Which of the following equations correctly represents the relationship between activity (A), decay constant ($\lambda$), and the number of radioactive nuclei (N)?
The half-life of a radioactive isotope depends on its initial mass.
The half-life of a radioactive isotope depends on its initial mass.
What does the decay constant signify in radioactive decay?
What does the decay constant signify in radioactive decay?
After two half-lives, a radioactive sample will have ______ of its original radioactive nuclei remaining.
After two half-lives, a radioactive sample will have ______ of its original radioactive nuclei remaining.
Which decay equation is correct?
Which decay equation is correct?
What is the primary reason the measured count rate of a radioactive sample is often less than its actual activity?
What is the primary reason the measured count rate of a radioactive sample is often less than its actual activity?
A negative value of activity represents a fundamental error in measurement.
A negative value of activity represents a fundamental error in measurement.
What adjustments must be applied to counter readings to account for machine errors?
What adjustments must be applied to counter readings to account for machine errors?
In a nuclear reaction, if uranium-235 absorbs a neutron and splits into molybdenum-95 and lanthanum-139, this process is an example of nuclear ______.
In a nuclear reaction, if uranium-235 absorbs a neutron and splits into molybdenum-95 and lanthanum-139, this process is an example of nuclear ______.
In nuclear fission, what characterizes the mass of the products compared to the reactants?
In nuclear fission, what characterizes the mass of the products compared to the reactants?
Match the particle with its property:
Match the particle with its property:
Flashcards
Mass Defect (Δm)
Mass Defect (Δm)
The difference in mass between a nucleus's individual components and the nucleus itself.
Binding Energy
Binding Energy
The minimum energy required to separate a nucleus into its individual nucleons at infinity.
Nuclear Fusion
Nuclear Fusion
Combining smaller, unstable nuclei to form larger, more stable nuclei.
Nuclear Fission
Nuclear Fission
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Radioactivity
Radioactivity
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Random Decay
Random Decay
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Spontaneous Decay
Spontaneous Decay
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Activity
Activity
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Decay Constant (λ)
Decay Constant (λ)
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Half-Life (T₁/₂)
Half-Life (T₁/₂)
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Study Notes
- A2 Physics 9702 - Radioactivity - Complete Notes
Nuclear Radioactivity
- Mass defect (Δm) is the difference in mass of a nucleus bounded atom and the mass of its individual components
- Δm = m(products) - m(reactants)
Binding Energy
- Binding energy is the minimum energy required to break a nucleus and separate its individual components at infinity
- E = Δmc²
- Binding energy tells you how stable a species is
- Binding energy is measured per nucleon
- Fusion is the combination of smaller unstable nuclei to form bigger stable nuclei
- Fission is the breaking of larger unstable nuclei into more stable daughter nuclei
Key Equations
- Binding energy per nucleon = 6.6 MeV
Determining if Aluminum Decays into Sodium
- The reaction 27Al -> 23Na + 4He is not energetically feasible, as Aluminum has more binding energy than the products
- Δm = m(products) - m(reactants)
- If Δm is positive, the reaction requires energy and is unfeasible
- If Δm is negative, the reaction gives off energy and is feasible
Radioactivity Concepts
- Radioactivity is the random and spontaneous decay of unstable nuclei emitting α, β, or γ particles
- Random decay implies an equal likelihood for any unstable nucleus to decay
- Spontaneous decay means the rate of decay of a radioactive sample does not depend on external factors
- Activity is measured in Becquerels (Bq), representing the rate of disintegrations per unit time
- A = -dN/dt, where dN/dt is the rate of change of the number of nuclei
- No - dN = N
- Activity is proportional to the number of unstable nuclei remaining, A = λN, where λ is the decay constant
Decay Constant
- Decay Constant = λ
- ΔN/Δt = λ x N
- λ = (-ΔN/Δt) / N
- The decay contant is the probability of an unstable nucleus decaying per unit time
Decay Equations
- N = No * e^(-λt), where N is the number of unstable nuclei remaining after time t
- No is the initial number of unstable nuclei
- A = Ao * e^(-λt)
- Half-Life (t1/2) is the time required for half the nuclei in the radioactive sample to decay
- t1/2 = ln(2) / λ
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