Nuclear instabilityAQA A-Level Physics: Flashcards

What these 14 flashcards ask

What does the N–Z graph of stable nuclei show?
Which decay do neutron-rich nuclei undergo?
Which decays do proton-rich nuclei undergo?
Which decay do very large nuclei undergo?
Changes in N and Z in alpha decay?
Changes in N and Z in β⁻ decay?
Changes in N and Z in β⁺ decay?
What is emitted with a β⁻ particle?
What is electron capture?
Which quantities are conserved in a decay equation?
Why is gamma emitted after alpha or beta decay?
How does gamma emission change N and Z?
What does a nuclear energy level diagram show?
Why is technetium-99m used in diagnosis?

Exam questions on Nuclear instability

Stable nuclei lie in a narrow band on a graph of neutron number N against proton number Z. For light nuclei the band follows the line N = Z, and for heavier nuclei it curves towards larger values of N than Z. Nuclei that lie outside the band are unstable and decay.
Uranium-238 is a heavy nucleus which decays by alpha emission. Explain, using the graph, why alpha emission suits heavy nuclei and what effect it has on N and Z.2 marks
Potassium-40 (⁴⁰₁₉K) is a radioactive isotope found in rocks and in the human body. It decays in two ways: by β⁻ emission to calcium-40, and by electron capture to argon-40.
Write a balanced equation for the electron capture of potassium-40 to argon-40.2 marks
Technetium-99m (⁹⁹ᵐTc) is a source of gamma radiation used in medical diagnosis. It is produced in a hospital by the decay of molybdenum-99, and the technetium-99m nucleus is left in an excited state that decays to the ground state of technetium-99 by emitting a single gamma photon of energy 140 keV. The half-life of technetium-99m is 6.0 hours.
Calculate the wavelength of the gamma photons emitted by technetium-99m.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).