A2 nuclear physics Flashcards
What happens during α decay?
In α decay, the nucleon number decreases by 4, and the proton number decreases by 2. The emitted particle is an alpha particle, represented as α.
What happens during β+ decay?
In β+ decay, a proton decays into a neutron, emitting a positron (β+) and a neutrino. The proton number decreases by 1.
What happens during β- decay?
In β- decay, a neutron decays into a proton, emitting an electron (β-) and an antineutrino. The proton number increases by 1.
What happens during γ decay?
In γ decay, a nucleus releases a gamma ray (γ) without any change in the nucleon or proton numbers
What is the law of conservation of mass in nuclear reactions?
The law of conservation of mass states that the total number of nucleons remains the same on both sides of the nuclear reaction equation.
In the reaction 92235 U + 01 n → 4295 Mo + 57139 La + 201 n + … + energy, what is the unknown particle?
The unknown particle is an electron (β-) because it has 0 nucleons, which satisfies the conservation of nucleon number
What is Einstein’s mass-energy equivalence equation?
E = Δmc², where E is energy, Δm is the mass defect, and c is the speed of light in a vacuum.
What is mass defect?
Mass defect is the difference between the total mass of individual nucleons and the mass of the nucleus.
What is binding energy?
Binding energy is the minimum energy required to separate all neutrons and protons in a nucleus. It is also the energy released when the nucleus is formed from its constituent nucleons.
What is binding energy per nucleon?
Binding energy per nucleon is the ratio of the total binding energy to the nucleon number, indicating the stability of the nucleus.
What is nuclear fission?
Fission is a process where a massive nucleus splits into two smaller nuclei, releasing energy. The fission fragments have higher binding energy per nucleon, making them more stable.
What is nuclear fusion?
Fusion is a process where two light nuclei combine to form a heavier nucleus, releasing energy. The binding energy per nucleon of the final nucleus is higher than that of the original nuclei.
What is the atomic mass unit (u)?
1 atomic mass unit (u) is defined as 1/12 of the mass of a neutral atom of carbon-12, approximately 1.661 × 10⁻²⁷ kg.
What is mass excess?
Mass excess is the difference between the mass of a nucleus (in atomic mass units) and its nucleon number.
Are radioactive processes spontaneous and random?
Yes, they are both spontaneous and random.
What does random mean in radioactivity?
Each nucleus has the same probability of decaying per unit time, and it’s impossible to predict when a nucleus will decay.
What does spontaneous mean in radioactivity?
The decay is not affected by external factors like temperature, pressure, or the presence of other nuclei.
What is the graph evidence for random decay?
Fluctuations in the count rate.
What is the graph evidence for spontaneous decay?
The graph shape stays the same even at different temperatures or pressures.
What is the rate of radioactive decay proportional to?
It is proportional to the number of undecayed nuclei (N).
What is the decay rate equation?
dN/dt = -λN
What is activity (A)?
Activity is the rate at which nuclei decay in a radioactive sample.
What is decay constant (λ)?
It is the probability that a single nucleus will decay per unit time.
What is the activity equation?
A = λN
What is the exponential decay formula?
x = x₀e^(-λt), where x can be activity, count, mass, etc.
What is half-life (t½)?
The time taken for half of the radioactive nuclei to decay.
How is half-life related to λ?
λ = 0.693 / t½
What is the relationship between decay constant and half-life?
They are inversely proportional.
