Radioactivity And Particles Flashcards
(28 cards)
Why are atoms neutral
Because the number of protons is equal to the number of electrons
What are isotopes
Atoms with the same number of protons but a different number of neutrons
Describe the process of radioactive decay
The breaking down of the nucleus of an isotope at random
It is unaffected by physical conditions e.g. temperature
In the process the nucleus often changes into a new element
What is background radiation and what are some examples
Radiation that is constantly present all around us in the environment
- substances from the earth e.g. air, soil, rocks
- living things
- human activity e.g. nuclear explosions or nuclear waste
Explain how radiation causes ionisation
Nuclear radiation collided into atoms and knocks electrons off of them causing them to turn into ions
The greater the penetrating power, the less ionising it is
What are alpha particles
What is their penetrating power
What is their ionising power
Are they deflected by anything
What is their effect on the atom they collide with
They are helium nuclei
Big, heavy, and slow moving
Very ionising but not very penetrating
They are positively charged so are deflected by electric and magnetic fields
They reduce the mass number by 4 and the atomic number by 2
What are beta particles
What is their penetrating power
What is their ionising power
Are they deflected by anything
What is their effect on the atom they collide with
They are an electron
They are quite small and quite fast
They are moderately penetrating and moderately ionsings
They are negatively charged so are deflected by electric and magnetic fields
They increase the atomic number by 1 and have no effect on the mass number
What are gamma rays
What is their penetrating power
What is their ionising power
Are they deflected by anything
What is their affect on the atom they collide with
Short wavelength EM waves
No mass
They highly penetrating but weakly ionising
They have no charge so are not deflected by anything
They always happen after beta or alpha decay
It has no effect on atomic number or mass number
What blocks alpha particles
Paper, skin, or a few cm of air
What blocks beta particles
Thin metal
What blocks gamma rays
Thick lead or very thick concrete
How can you investigate the penetration of radiation using a Geiger-Muller detector
Find the background count rate by removing all sources, divide the number of counts by the time period and do this 3 times to calculate a mean average, remove this from all of your results
Replace the source and measure the count rate with no material present, and repeat + calculate mean average
Place different materials between the source and the detector, and measure the count rate, and repeat + calculate mean average
If the count rate is similar, then it is penetrating the material whereas if it lowers, then it is getting absorbed
Repeat using different sources to measure the penetrations of different sources
What precautions can you take to reduce the risk of radiation
Keep radioactive sources in a lead-lined box when not in use
Use forceps or long-handled tongs when picking them up
Do not point them at anyone and maintain a safe distance from them
What is Half-life
The time taken for half of the radioactive atoms now present to decay
Describe how medical tracers work
A short half-life Beta or Gamma source is injected into the patient where it penetrates into their tissues and can be detected externally, as the source moves around the body, the radiographer uses a detector and a computer to monitor its progress on a display
This is used to ensure the organs are working as they should
How is radiation used to treat cancer
Radiotherapy involves a high dose of gamma rays is zapped into the cells in the tumour, this kills or damages the cells while minimising the dose to the rest of the body
How is radiation involved in food and equipment sterilisation
High does of gamma rays kill all microbes so that medical equipment is sterilised and food doesn’t go bad as quickly as it might have done within the presence of microbes
It is better than boiling as it reduces risk of damage due to absence of high temperatures
Long half-life (at least 7 months)gamma rays are better so it does not need replacing too often
How is radiation used to detect leaks in underground pipes
Gamma radiation source/tracer is used and allowed to flow down the pipe
A detector is used above the ground
If the pipe does have a crack, then more radiation will accumulate outside the pipe, causing the detector to show extra high radioactivity at that point
How can radiation be used in thickness control
E.g. paper, direct beta radiation through the paper being made and put a detector on the other side connected to a control unit, when the detected radiation changes, this means the paper is coming out to thick or thin
It needs to be beta radiation as then the paper will partly block the radiation causing a change in the reading
What is irradiation
The exposure to radiation
What are the risks of alpha radiation
Dangerous if it gets inside your body
What are the risks of Beta and Gamma radiation
Penetrate the skin and soft tissues to reach the delicate organs inside the body
What happens when radiation enters the body
Will collide with molecules inside your cells, resulting in ionisation
Lower doses cause minor damages without killing the cell e.g. mutations which can divide uncontrollably, resulting in cancer
Higher doses tend to kill cells completely, causing radiation sickness if a large part of your body is affected at the same time
What is contamination
Unwanted radioactive atoms getting onto or into an object
Protective suits and masks prevent breathing in these particles
Gloves and tongs prevent the particles getting stuck to your skin when handling them
