P7: Radioactivity Flashcards
What is the radius of an atom?
1 x 10^-10 meters
What is count-rate?
The number of decays recorded each second by a detector
What is an alpha particle?
2 neutrons and 2 protons which is the same as helium
What is a beta particle?
A high speed electron ejected from the nucleus as a neutron turns into a proton
What is a gamma particle?
Electromagnetic radiation from the nucleus
What is a half-life?
The time it takes for the number of
What is radioactive contamination?
The unwanted presence of materials containing radioactive atoms on other materials
What is irradiation?
The exposing an object to nuclear radiation, and the irradiated object does not become radioactive
Where does background radiation come from?
Either natural sources like rocks and cosmic rays, or man made sources like fallout from nuclear weapon testing and nuclear accidents
How are nuclear radiations used in medicine?
Exploration of internal organs and control or destruction of unwanted tissue
Describe the process of fission
Nucleus is split into 2 smaller nuclei, and emits 2 or 3 neutrons plus gamma rays.
How is a chain reaction controlled?
In a nuclear reactor to control energy released.
What causes an explosion in a nuclear weapon?
Uncontrolled chain reaction
What is the source of a beta particle?
A neutron decaying into a proton and an electron
What determines how harmful radiation is?
Type of radiation, where you’re exposed and the amount you receive
How can irradiation be minimsed?
Wear protective gear, keeping item in lead-lined box and handle with tongs
What factors affect the amount of radiation you receive?
How long you’re exposed to the substance, how radioactive it is and how far away from the source you are
What are 2 ways radiation can treat cancer?
Gamma rays are emitted to cancer and internally, by placing radioactive source near cancer source and uses beta radiation
Evaluate the use of medical tracers and radiotherapy for treatment
Medical tracers help diagnoses, so worth the risk, however low doses and ones with a short half-life are needed to minimise risk. Radiotherapy can save a person’s life, but it only extends life for a short period.
What are side effects of radiotherapy?
Healthy cells will be killed, making the patient ill
What are the pros of nuclear energy?
Uranium and plutonium is relatively cheap, produces a large and steady amount of energy and does not release greenhouse gases
What are the cons of nuclear energy?
Power plants are expensive to build, nuclear waste is expensive to get rid of and there is a risk of major disaster
What is the process that fuels stars?
Nuclear fusion
Why does fusion release tons of energy?
Because the mass of original nuclei is being converted to energy
Why does nuclear fusion only happen in stars?
Because of the high temperatures and pressures that are required
Why does fusion only happen at very high temperatures and pressures?
To overcome the repulsion of positively charged nuclei
