Isotopes are more stable when there is a balanced ratio of protons to neutrons and a high binding energy per nucleon.
Strong nuclear force holds nucleons together, but large nuclei experience greater repulsive electrostatic forces, leading to instability.
Nuclei can undergo alpha decay, beta decay, or gamma emission to achieve a more stable energy configuration.
Alpha decay reduces both mass and charge by emitting a helium nucleus, decreasing nuclear size.
Beta decay changes a neutron into a proton (or vice versa), adjusting the proton-neutron ratio for greater stability.
Gamma decay allows the nucleus to release excess energy without changing its composition, often following alpha or beta decay.
Although each individual decay is random and spontaneous, the overall behavior of a large sample follows a predictable half-life pattern.
Activity (A) and count rate decrease exponentially, and predictions about the remaining quantity of radioactive material can be made using the number of half-lives.
Statistical laws ensure accurate average behavior, even though specific decay events are unpredictable.
isotopes
nuclear binding energy and mass defect
the variation of the binding energy per nucleon with nucleon number
the mass-energy equivalence in nuclear reactions
the existence of the strong nuclear force, a short-range, attractive force between nucleons
the random and spontaneous nature of radioactive decay
the changes in the state of the nucleus following alpha, beta and gamma radioactive decay
the radioactive decay equations
the existence of neutrinos and antineutrinos
the penetration and ionising ability of alpha particles, beta particles and gamma rays
the activity, count rate and half-life in radioactive decay
the changes in activity and count rate during radioactive decay using integer values of half-life
the effect of background radiation on count rate.
the evidence for the strong nuclear force
the role of the ratio of neutrons to protons for the stability of nuclides
the approximate constancy of binding energy curve above a nucleon number of 60
that the spectrum of alpha and gamma radiations provides evidence for discrete nuclear energy levels
the continuous spectrum of beta decay as evidence for the neutrino
the decay constant and the radioactive decay law
that the decay constant approximates the probability of decay in unit time only in the limit of sufficiently small λt
the activity as the rate of decay
the relationship between half-life and the decay constant