Radioactivity and Particles Flashcards
The atomic notation:
Atomic mass - A
Atomic number - Z
The stability of isotopes:
There is a nuclear force holding the protons together in the nucleus. The presence of neutrons affects the balance between the repulsion and nuclear forces. Too many or too few neutrons would make the nucleus unstable which will eventually decay by emitting ionizing radiation
Properties of alpha radiation:
- Fast-moving particles
- Helium nuclei
- Large mass
- Charge: +2
- Low penetrating power
- High ionizing power
Properties of beta radiation:
- Fast-moving electrons
- Light (mass)
- Charge: -1
- More penetrating power
- Less ionizing power
Properties of gamma radiation:
- Electromagnetic wave
- No mass and no charge
- Photons
- Most penetrating
- Least ionizing
The symbol used for neutron in radioactive decay:
¹n₀
The speciality of neutron emission:
It can be absorbed by other atoms and makes them radioactive
Changes in alpha decay:
Mass no. decreases by 4
Atomic no. decreases by 2
Changes in beta decay:
Mass no. doesn’t change
Atomic no. goes up by one
Changes in neutron emission:
Mass no. goes down by one
Atomic no. doesn’t change
Unit of radioactivity:
Bq
What is Becquerel?
A measure of how many unstable nuclei are disintegrating per second
Set up of GM tube:
Mica sheet
Glass tube
Conducting surface
Central electrode connected to a detecting circuit: a counting circuit or a rate meter (loudspeaker)
Sources of background radiation:
- Radioactive rocks: radon gas
- Cosmic rays from exploding stars and Sun
- Living things: C-14
- Nuclear power stations, nuclear weapons
- Medical use eg. tracers
What is the relationship between the decay and the no. of nuclei?
The rate of decay falls as time passes because there are fewer nuclei to decay
Advantages of gamma radiography over X-rays:
- Gamma source can be in small amounts
- Don’t require a power source
- Don’t require large equipment
Advantages of gauging using radioactive isotopes:
- No contact with the material being gauged
- Coal dust can cause false readings with optical gauging systems
A decay product of radium:
Radon gas
Example of alpha emitter:
Radon gas
Ways of detecting ionizing radiation?
GM tube
Photographic film
Badges using the thermoluminescence property
What is thermoluminescence?
Thermoluminescence means that the exposed material will give out light when it becomes hot
Safe handling of radioactive materials:
- Lead-lined boxes
- Labelled as hazardous
- Placed in a metal cabinet
- Use tongs
- Hold away from your body
- Spent uranium fuel rods from nuclear reactors are stored underwater until neutron radiation levels drop to a safe level
Use of carbon dating:
To find the age of organic matter
Limitations on carbon dating:
- It assumes the levels of cosmic rays reaching the Earth to be constant, which can
be inaccurate - Can’t be used to date samples older than 50,000 to 60,000 years because after 10 years the sample because the amount of C-14 becomes too small to measure accurately
