Atoms and Nuclear Radiation Flashcards
Why do unstable nuclei give out radiation?
- Unstable nuclei undergo decay to become more stable
- As they release radiation, they become more stable
What is radioactive decay?
When an unstable nucleus gives out radiation in order to become more stable
Define ‘activity’ in an unstable nucleus
Activity is the rate of decay at a source of unstable nuclei
What is the unit of radioactive decay?
Becquerels (bq)
What is count rate?
- Count rate is the number of radioactive decays per second
- From a radioactive source
Example of a detector that may be used to measure count rate?
Geiger-Muller tube
Four types of nuclear radiation :
- Alpha particles
- Beta particles
- Gamma rays
- Neutrons
What does an alpha particle consist of?
- Two protons
- Two neutrons
- SAME AS THE HELIUM NUCLEUS
Range of alpha particle through hair?
A few centimerers (2-10)
What stops beta radiation from passing through a point?
- A thin sheet of aluminium
- Or several metres of air
What will stop gamma radiation from passing through a point?
- Several centimetres of lead
- Or a few metres of concrete
Which type of radiation is most ionising?
Alpha radiation
Which type of radiation is least ionising?
Gamma radiation
What changes when a gamma ray is radiated?
- No change to charge
- No change to mass
What is the nature of radioactive decay life?
- RANDOM
- Impossible to predict which nuclei will decay and when
What is the half life of a radioactive isotope?
The time that it takes for the count rate of a radioactive substance to half from its original level
What is radioactive contamination?
The presence of unwanted radioactive nuclei on other materials
What is irridation?
- Exposing a material to nuclear radiation
- That does NOT become radioactive
- Can kill living cells
What is peer review?
- When studies are published and shared with other scientists
- To allow findings to be individually checked
- For flaws or errors
How can radiation be used?
In smoke detectors
How do smoke detectors work?
- Alpha emitter emits alpha particles
- However is blocked as the smoke passes through
- So the sensor detects change
- Sounds the alarm
How can irritation be used?
- Sterilising surgical equipment
- Food can be irradiated to kill any unwanted microbes
What is contamination in terms of radiation?
When a source becomes unwantedly radioactive and emits radiation
