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
● Alpha particles
● Beta particles
● Gamma rays
● Neutrons
What are the constituents of an alpha particle?
Two protons and two neutrons. It’s the same as a helium nucleus.
What is the range of an alpha particle through air?
A few centimeters (normally in the range of 2-10 centimeters).
What will stop beta radiation from passing through a point?
A thin sheet of aluminium or several meters of air
What will stop gamma radiation from passing through a point?
Several centimeters of lead or a few meters 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 remained 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.
