Topic 7: Half-life Flashcards
How does radioactive decay ‘behave’?
It is random and spontaneous (unpredictable).
What is the definition of a half life?
The time taken for the activity of a sample to halve.
What is activity?
A measure of radioactive decay per second. (aka count rate)
What is activity measured in?
Bq - becquerels
How is the half-life found on a decay curve?
The top value is halved
a line is drawn to the time at the half value.
How can beta emitting radioactive isotopes be used?
To measure the thickness of aluminium foil.
Fewer beta particles will pass through when the thickness of aluminium increases.
How can gamma emitting radioactive isotopes be used?
Can be used as a medical tracer in monitoring internal organs by using a camera.
Gamma= less harmful to body, easily passes out of it.
How can alpha emitting isotopes be used?
Smoke detectors.
Gamma= too penetrating, wont be blocked by smoke
Beta= can travel a (around) a metre through smoke
What type of radiation is used for externally treating cancer?
Gamma - beamed at cancer cells to kill them.
What type of radiation is used for internally treating cancer?
short half-life alpha - injected into tumours.
Weakly penetrating, won’t harm other cells.
What is carbon dating?
A technique which uses the radioactive isotope carbon-14 to date ancient organic artefacts.
Carbon-14= beta emitter, half-life of 5730 years
