Radioactivity
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What are radioactive elements?
Have atoms that have unstable nuclei because of unstable combinations of protons & neutrons.
What is the process of radioactive decay?
Unstable atoms disintegrate or decay to form smaller, more stable atoms They emit radiation when this happens
What are the properties of alpha rays? How are they stopped? What is its charge?
Large, heavy, slow particles, Helium atoms that’s lost 2 electrons Few cms of air, Thin sheet of paper Positive
What is background radiation? Sources?
Radiation that’s all around us & always present, caused by reaction of unstable nuclei Radon Carbon-14 Cosmic rays Nuclear reactors
What are everyday uses of radiation?
Gamma rays: kill cancer cells , Sterilise surgical instruments, Preserve perishable fish food, Detects leaks from underground pipes
What happens when radiation is emitted?
Original element disintegrates into new element & smaller more stable atom formed
What are the properties of beta rays? How are they stopped? What is its charge?
Small, light & fast-moving electrons Few metres of air, Few mms of aluminium Negative
What are the properties of gamma rays? How are they stopped? What is its charge?
Fast & powerful electromagnetic radiation Few cms of lead None
What is carbon-14 radiation?
Type of carbon found inside all living organisms
What is radon radiation?
Radioactive gas emitted from granite rocks
What is potassium radiation?
Measurable traces contained in some foods
What are nuclear reactors radiation?
Waste from nuclear power stations
What are radioactive materials radiation?
Used in medicine in hospitals
What are cosmic rays radiation?
Rays reaching earth from space
What is the definition of a half-life?
Time taken for radiation to fall by half
What is ionisation?
Process of electrically neutral atoms becoming ions by radiation
What is the common name for Alpha, Beta & Gamma rays?
Ionising radiations, as they cause ionisation
How do we minimise risk form ionising radiation?
Maximise distance from person & radioactive source - at arms length, with tongs facing away from user Minimise exposure time - work quickly, but carefully, kept in locked lead-lined container at all other times Shield observer from source
How is radiation used in industry?
Leaks from pipeline carrying oil or gas can be traced by injecting radioactive element into to it. Saves digging it all up Right element should: Have a half-life of few hours or days - long enough to be detected, short enough that isn’t safety problem Be a beta emitter - alpha particles absorbed by soil, gamma rays would pass through medical pipe
How is radiation used in medicine?
Used to kill cancer cells, gamma rays used as they can penetrate deep inside body, and can target tumour Radiation source rotated to have maximum effect on cancer cells, but not destroy healthy cells surrounding tumour Measures put in place to reduce harm to patients, e.g. radiotherapy treatment in series of very small doses
How is radiation used in sterilisation?
Gamma rays sterilise plastic syringes, which would be damaged by heating them