P4 - Atoms and Nuclear Radiation Flashcards
Why and how 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.
Activity
Rate at which source of unstable nuclei decay
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.
- Alpha particles
- Beta particles
- Gamma rays
- Neutrons
What does an alpha particle consist of?
● 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 they decay is determined only by chance
● It is impossible to predict which nuclei will decay and when
