Atomic Structure Flashcards
What cab be used to protect against irridation when using radioactive sources?
-Use source with lowest activity for shortest amount of time possible
-Appropriate clothing: lead apron
- Not handling source with bare hands
How does nuclear weapon cause an explosion?
Explosion caused by a nuclear weapon the result of an unctrolled chain reaction
What does a contaminated object do?
Gives out radiation until decontaminated
Why does an unstable nuclei give out radiation?
To become more stable
What decreases in alpha decay?.
Mass and charge
What is the difference between nuclear fission and fusion?
Nucleus fission= splitting of large nuclei
Nuclear fusion= joining of small nuclei
Why is more dangerous food contaminated with gamma or alpha?
Food contaminated with alpha would be more hazardous than gamma as alpha is more ionising
What source of radiation makes the best medical tracers?
Gamma
- Penetrate body and detected on outside of body
- Least ionising
Describe gamma?
Poorly ionising, electromagnetic radiation wave emitted from nucleus, pass through living cells without being absorbed
What is contamination?
Unwanted presence of materials containing radioactive atoms
Where is background radiation from?
Around us all the time.
Depends on location and occupation
87% from natural sources
13% from man made sources
What is nuclear fission?
(Fission is division)
-Splitting of large unstable nucleus (uranium or putonium)
-Doesn’t occur by itself, must absorb a neutron first
- Nucleus splits into 2 smaller nuclei -Emits 2 or 3 gamma rays and energy
- All products have kinetic energy
-Neutrons emitted start a chain reaction
Describe beta?
Moderately ionising, cause damage if absorbed by living cells, high speed electron ejected from nucleus as neutron turns into proton
What is nuclear fusion?
(Fusion = fuse together)
-Opposite of fission
- Two daughter nuclei join to form a heavier nucleus
- Some mass converted to energy, some of this energy may be emitted as radiation
Why does nuclear fusion require very high temperatures and pressure?
To overcome electrostatic repulsion
Bring (+) nuclei close enough for fusion to happen
Describe isotopes with short half lives?
-Very unstable, emit radiation very quickly, exposure is hazardous
- Don’t remain radioactive for long
What is more dangerous area contaminated with alpha or gamma?
Area contaminated with alpha source wouldn’t be as dangerous as area contaminated with gamma as gamma is very penetrative
What is irridation?
Expose object to nuclear radiation, object not radioactive
What is the 4th type of nuclear radiation?
A neutron (n) can be emailed during radioactive decay
Describe isotopes with long half lives?
-More stable
- Remains radioactive for longer
-Emit radiation slowly, exposure less hazardous
Alpha decay equation?
- 4
AM. —– NP. + He
- 4
- 2
Describe alpha decay?
2 neutron and 2 protons ejected from nucleus, highly likely to be absorbed, cause damage if passing through living cells, strong ionising power
What is the activity of a radioactive source?
Is the rate at which it decays, measure in becquerels (Bq)
What are medical tracers used for?
To look at internal organs:
Radioactive isotope invested or injected, can be detected outside as it travels around body
How does a medical tracers detect kidney problems?
Isotope that will pass through the kidneys is used. If it builds up in one kidney and not the other, it could indicate that obesity of the kidneys isn’t working efficency
How can nuclear radiation treat tumours?
Tumour in thyroid gland treated with radioactive iodine, gathers in gland and destroys nearby cells. OR focused beam of gamma ray can destroy some tumours
What is half life used to find ?
The activity of a source after a certain time
Beta decay?
- 0
C. ——- N. + e
- 0
- -1
Gamma, beta and alpha in terms of penetration?
-Alpha, only reaches paper, less penetrating
-Beta only reaches aluminiumum, medium penetration
-Gamma reaches lead, most penetrating
What is half life?
Time it takes for half the nuclei ti decay
