7 RADIOACTIVITY + PARTICLES Flashcards
Unit for radioactivity
Becquerel (Bq)
Larger number of atom
Mass (nucleon) number
Larger number of an atom
Mass (nucleon) number
Smaller number of an atom
Atomic (proton) number
Where does radiation come from
Emitted randomly from an unstable nucleus
Nature of alpha
Helium nucleus
Nature of beta
Fast-moving electron
Nature of gamma
Very high frequency electromagnetic wave
Mass of alpha
4
Mass of electron
1/1840
Mass of gamma
0
Charge of alpha
2+
Charge of beta
1-
Charge of gamma
0
Penetrating power of alpha
Low
Penetrating power of beta
Medium
Penetrating power of gamma
High
Ionising power of alpha
High
Ionising power of beta
Medium
Ionising power of gamma
Low
What stops alpha
Paper and thin aluminium
What stops beta
Aluminium
What stops gamma
Lead and concrete
What is contamination
When radioisotopes get inside an object, making the object itself radioactive
What is irradiation
When radiation passes through an object causing damage due to ionisation, but not leaving the object itself radioactive
Effect on mass number of new nucleus from alpha release
-4
Effect on mass number of new nucleus from beta release
0
Effect on mass number of new nucleus from gamma release
0
Effect on mass number of new nucleus from positron release
0
Effect on atomic number of new nucleus from alpha release
-2
Effect on atomic number of new nucleus from beta release
1+
Effect on atomic number of new nucleus from gamma release
0
Effect on atomic number of new nucleus from positron release
1-
Define half-life
The time taken for half the radioactive nuclei to decay
What can detect ionising radiation
A geiger-muller detector, OR a photographic film
Where does background radiation come from
- Cosmic rays
- Rocks
- Medical equipment (x-rays)
Uses of radiation
- Medical tracers
- Sterilising food/equipment
- Thickness control
- Smoke detectors
Dangers of radiation
- Cause mutations in living organisms
- Cause cell + tissue damage
- Cause skin burns
How do you dispose of radioactive waste
- Bury deep in concrete
- Bury in ocean
- Bury deep in earth
How do you dispose of radioactive waste
- Bury deep in concrete
- Bury in ocean
- Bury deep in earth
Describe how power is generated in a nuclear power station
U-235 is bombared with slow-moving neutrons to split the nucleus into 2 daughter nuceli and some neutrons
Function of control rods
Absorb extra neutrons to prevent a chain reaction
Function of moderator
Slow neutrons to ensure they split nuclei
Function of sheilding
Keeps radiation inside - protection
What does a star get it’s energy source from
Nucluer fusion
Nature of fusion
Joining of 2 light helium nuclei
Nature of fission
Splitting of a heavy U-235 nucleus
Condition for fission
Neutron must be moderated to a slower speed
Condition for fission
Neutron must be moderated to a slower speed
Why can fusion only occur at high pressures and temperatures
As it needs to overcome the electrostatic repulsion force between protons
Disadvantage of fission
Produces radioactive waste
End product of fission
2 daughter nuclei and some neutrons
End product of fusion
A helium nucleus
How does a chain reaction occur
Neutrons produced by one fission split other U-235 nuclei
