Topic 4-Atomic structure Flashcards
Where does radioactivity come from?
Given off by radioactive isotopes or unstable nuclei
What is an alpha particle made up of?
2 protons and 2 neutrons (+2) (mass of 4)
It is the same as a helium nucleus
What is a beta particle made up of?
1 high energy electron (-1)( mass of basically 0)
What is a gamma particle made up?
It is a wave
No charge
No mass
What are the characteristics of an alpha particle
- Highly ionising
- Weakly penetrating
- Can be stopped by a few cm of air, paper, skin
What are the characteristics of a beta particle?
- Medium ionising
- Medium penetrating
- Can be stopped by few m of air or aluminium
What does it mean if something is ionising?
It means it creates an ion
What are some of the characteristics of a gamma particle?
- Low ionising
- Highly penetration
What are some of the uses of alpha, beta and gamma particles?
Alpha- smoke detectors
Beta- Check thickness of paper
Gamma- Sterilisation or radiotherapy
Why do unstable nuclei give out radiation?
- Unstable nuclei undergo decay to become more stable
- As they release radiation their stability increases
What does ‘half-life’ mean?
It is the time taken for half the nuclei in a sample to decay
It cannot be predicted
How can you protect yourself from radiation?
- Reduce time with radiation
- Stand far away
- Use gloves/screen
What is the unit of radioactive activity?
Becquerel (Bq)
Give an example of a detector that may be used to measure count-rate?
Geiger-Muller tube
Describe the nature of radioactive decay
- Random
- Which nuclei decays and when is determined only chance
- It is impossible to predict which nuclei will decay and when
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
- This is known as peer review
How should background radiation be dealt with in calculations?
The background count should be subtracted from any readings before calculations are attmepted
Why might the radiation dosage that different people experience differ?
- Some occupations involve working with radiation
- Background radiation differs with location due to things such as the locality of nuclear power stations or radiation related testing
Explain why contamination of the inside of the human body by a radioactive material that emits alpha radiation is highly dangerous
Alpha particles are highly ionising. This can cause organ failure and radiation sickness until the radioactive material is removed
