9702 · 11.1
Atoms, nuclei and radiation flashcards
Revision flashcards for Cambridge 9702 Atoms, nuclei and radiation (syllabus 11.1). Flip, recall, then mark a real past-paper question.
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What key discovery about atomic structure came from Rutherford's scattering experiment?
Atoms are mostly empty space with a very small, dense, positively charged nucleus.
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How is the nucleon number (A) of an atom determined?
It's the total count of protons and neutrons in the nucleus (A = Z + N).
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Describe the difference between beta-minus ($\beta^-$) and beta-plus ($\beta^+$) decay in terms of quark transformation.
In $\beta^-$ decay, a down quark changes to an up quark (d → u + e⁻ + ν̅ₑ); in $\beta^+$ decay, an up quark changes to a down quark (u → d + e⁺ + νₑ).
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What are the fundamental constituents of a hadron, and what are the two main types?
Hadrons are made of quarks; the two main types are baryons (three quarks) and mesons (one quark and one antiquark).
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List the three conservation laws that apply to all nuclear processes.
Conservation of total charge, nucleon number, and lepton number.
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Define specific charge.
Specific charge is the ratio of a particle's charge to its mass (Charge/Mass).
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How do isotopes of an element differ?
Isotopes of an element have the same proton number (Z) but different numbers of neutrons (N).
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What is an alpha particle?
An alpha particle is a helium nucleus, consisting of two protons and two neutrons ($_2^4\text{He}$).
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What is gamma radiation?
Gamma radiation consists of high-energy electromagnetic photons, typically emitted from an excited nucleus after an alpha or beta decay event.
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What is an antiparticle?
An antiparticle has the same mass as its corresponding particle but opposite charge and quantum numbers.
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What is the quark composition of a neutron?
A neutron is a baryon made of one 'up' quark and two 'down' quarks (udd).
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Compare the relative ionising abilities of alpha, beta, and gamma radiation.
Alpha radiation is the most ionising, beta is moderately ionising, and gamma is the least ionising.
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What role does the strong nuclear force play in an atom?
It is an attractive force that binds protons and neutrons together in the nucleus, overcoming the electrostatic repulsion between the positively charged protons.
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How do the nucleon number (A) and proton number (Z) change during beta-plus ($\beta^+$) decay?
The nucleon number (A) remains unchanged, while the proton number (Z) decreases by 1.
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What defines a particle as a lepton?
A lepton is a fundamental particle that does not experience the strong nuclear interaction. Examples include electrons and neutrinos.