Radioactivity Flashcards
Neutron
Found in the nucleus, 1 mass, no charge
Proton
Found in the nucleus, 1 mass, positive charge
Electron
Found in the shell, negligible mass, negative charge
Atomic number
The number of protons in an atom
Mass number
The total number of protons and neutrons in the nucleus of an atom
Isotope
Different atoms of the same element, with the same number of protons but a different number of neutrons. Also have the same chemical properties
What are alpha and betas particles and gamma rays?
Ionising radiations emitted from unstable nuclei in a random process
Alpha (Composition, Charge, Mass, Speed, Penetrability, Ionisation, Stopped by, Deflected by)
- 2 protons + 2 neutrons
- +2
- 4
- Slow
- Low penetrating power
- High ionising radiation
- Stopped by paper
- Charged so it’s deflected by a magnetic field
Beta (Composition, Charge, Mass, Speed, Penetrability, Ionisation, Stopped by, Deflected by)
- The same as an electron
- -1
- 1/2000 of a proton
- Fast
- Medium penetrating power
- Moderate ionising radiation
- Stopped by aluminium
- Charged so it’s deflected by a magnetic field
Gamma (Composition, Charge, Mass, Speed, Penetrability, Ionisation, Stopped by, Deflected by)
- An EM wave
- No charge
- No mass
- Speed of light
- High penetrating power
- Very low ionising radiation
- Stopped by lead/concrete
- Not deflected by a magnetic field
What can detect ionising radiation?
Photographic film or a Geiger-Muller detector
What is background radiation?
Naturally occurring radiation around us
What are some sources of background radiation?
Rocks/soil, food, cosmic rays, medical treatments and more
What happens to the activity of a sample over time?
It decreases
How is the activity of a sample measured?
In Becquerels
Half-life
The length of time it takes for the activity of an amount of radioactive substance to half
Uses of radioactivity
Medical tracers
- Half-life of 3-8 hours depending upon use
- β or γ emitters
Tracers for pipes
- Half-life of 3-8 days
- γ emitters
- Used to detect breaks along blockages
Features of irradiation
- Occurs when an object is exposed to an outside source
- Doesn’t cause the object to become radioactive
- Can be blocked by adequate shielding
- Stops as soon as the source is removed
- Used for sterilising food and medical equipment and gamma cancer treatments
Features of contamination
- Occurs if the source is on or in the object
- Object will be radioactive for as long as the source is in it
- The radiation cannot be blocked from the object
- It can be very difficult to remove all of the contamination
- Used for tracers
What can ionising radiation cause?
Cell and DNA mutations
Protection from radiation
Protective clothing
- Radiation suits
- Lead aprons
- Masks and glasses
Limit exposure time
- Radiation badges to measure
- Leaving the room for medical reasons
Handle sources with care
- Stored in a lead-lined box
- Handle with tongs
Why is long-term storage a major problem with nuclear materials?
Some materials have extremely long half-lives so they remain active for thousands of years. Nuclear waste must be stored in sealed containers that must be capable of storing the radioactivity. It is stored deep underground in lead-lined containers far away from civilisation
