Topic 4 - Atomic Structure - 4.2 - Atoms and Nuclear Radiation Flashcards
Why do unstable nuclei give out
radiation?
●Unstable nuclei undergo decay to become more stable
●As they release radiation their stability increases
What is the name of the process in which an unstable nucleus gives out radiation to become more stable?
Radioactive decay.
Define the activity of an unstable
nucleus.
Activity is the rate of decay of a source of
unstable nuclei.
What is the unit of radioactive activity?
Becquerel (Bq)
What is count-rate?
The number of radioactive decays per
second for a radioactive source.
Give an example of a detector that may
be used to measure count-rate.
Geiger-Muller tube
State four types of nuclear radiation.
What are the constituents of an alpha
particle?
●Two protons and two neutrons
● It is the same as a helium nucleus
What is the range of an alpha particle
through air?
A few centimetres (normally in the range
of 2-10cm).
What will stop beta radiation from
passing through a point?
●A thin sheet of aluminium
●Several metres of air
What will stop gamma radiation from
passing through a point?
●Several centimetres of lead
●A few metres of concrete
Which type of radiation is most ionising?
Alpha radiation.
Which type of radiation is least ionising?
Gamma radiation.
State any changes to mass or charge that occur due to the emission of a gamma ray.
Both mass and charge remain
unchanged.
Describe the nature of radioactive decay.
●Random
●Which nuclei decays and when is determined only by chance
● It is impossible to predict which nuclei will decay and when
