AQA GCSE Combined Science Trilogy · 8464
Specification 6.4.2.3 · Paper 5
Revise: Half-Lives and Radioactive DecayHalf-life describes this pattern; it is not a countdown telling us when each nucleus will decay.
Loading…
Loading…
Loading…
GCSE Combined Science · key term
The time taken for the number of nuclei of a radioactive isotope in a sample to halve, or for the sample’s count rate or activity to fall to half its initial level.
Used by AQA and Edexcel
Specification 6.4.2.3 · Paper 5
Revise: Half-Lives and Radioactive DecayHalf-life describes this pattern; it is not a countdown telling us when each nucleus will decay.
Paper 5, Paper 6
The time taken for half the undecayed nuclei of a radioactive isotope to decay, or for the activity of a source to fall to half its value.
Revise: Activity and half-lifeThe half-life of a radioactive isotope is the time taken for half its undecayed nuclei to decay. Equivalently, it is the time taken for the activity of a source to fall to half its value.
On a decay graph, find half the starting value, read the corresponding time and subtract the starting time. A half-life is a time interval.
Each half-life halves the amount still remaining; it does not remove half of the original amount every time.
Define half-life using half the undecayed nuclei or half the activity, not half the total number of atoms.
Create a free account to read GCSE Combined Science revision notes for your exam board and track your progress.