4.4.2 P1 Atoms and Nuclear Radiation (might come up) 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 decay
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
4 types of nuclear radiation
Alpha particles
Beta particles
Gamma rays
Neutrons
What is an alpha particle
2 protons and 2 neutrons
Same as a helium nucleus
What is the range of an alpha particle through air
A few centimetres
normally between 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
Why 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
Define the half-life of a radioactive isotope
The time it takes for the number of unstable nuclei in a substance to halve
The time it takes for the count rate from a sample to fall to half its initial level
What is radioactive contamination
The presence of unwanted radioactive nuclei on other materials
What is irradiation
The process of exposing a material to nuclear radiation
The material does not become radioactive
Why is it important for the results of studies on the effects of radiation to be published and shared with other scientists
To allow the findings to be independently checked
Peer review
What is a beta particle made from
When a neutron turns into a proton and emits a fast moving electron
Mass of an electron
Charge of an electron
0
-1
What is a gamma ray
An electromagnetic wave
Most penetrating radiation
Gamma rays
Least penetrating radiation
Alpha
