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Beschreibung
Karteikarten von Kelly Jowett, aktualisiert more than 1 year ago
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Erstellt von Kelly Jowett
vor mehr als 9 Jahre
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| Frage | Antworten |
| what is an isotope? | an element with different amount of neutrons |
| what is the stability like of an isotope? | unstable |
| what kind of nuclei produces a radioactive element? | an unstable one |
| what happens when nuclei decay? | they give out ionising radiation |
| what are the three types of ionising radiation? | beta, alpha, gamma |
| what element does alpha radiation cause? | helium |
| what is the size and the speed of movement for an alpha particle? | big, heavy and slow moving |
| what material can block the route of a alpha particle? | paper |
| what does a beta particle cause? | a neutron to turn into a proton |
| what is a beta particle? | an electron |
| what is the size and speed of movement like for a beta particle? | middle |
| what is the charge of a beta particle? | -1 |
| what material blocks a beta particle? | aluminium |
| what ionising strength does gamma have? | weak |
| what is gamma? | an em wave |
| what change does gamma radiation do to an element? | none - no change to element or charge |
| what blocks gamma radiation? | thick lead |
| what sort of ionising strength does an alpha particle have? | strong |
| what is the charge of an alpha particle? | 2+ |
| when is gamma often released? | after beta or alpha the nucleus gets rid of extra energy |
| what is the nuclear equation for alpha? | mass -4 4 0 element -> new element + he + y atomic -2 2 0 |
| what is the nuclear equation for beta? | mass same 0 element -> new element + e atomic +1 -1 |
| where is beta radiation used? | *thickness control of paper (eg) *medical tracers |
| where is alpha radiation used? | *smoke alarms |
| where is gamma radiation used? | *medical tracers *radiotherapy (killing cancer cells) *sterilising food and medical equipment |
| what occupations run a high risk of being contaminated by radiation? | *radiographers *pilots *miners *nuclear power station workers |
| how can the risks of contamination of radiation be reduced? | *wearing protective clothing *avoiding the radiation as much as possible *having regular health check ups |
| the damage of radiation contamination to health depends on what things? | *dose *type *amount of exposure |
| what does high doses of radiation increase the risk of? | cancer |
| what is radiation measured in? | sieverts or millisieverts (Sv or mSv) |
| what is half life? | the average time for the number of unstable nuclei in a radioactive isotope to halve |
| can it be predicted when a nucleus will decay? | no |
| what causes a particle to be strongly ionising? | the electrons are easily knocked out |
| what is radioactivity measured in? | bequerels (Bq) |
| where does background radiation come from? | naturally occurring unstable isotopes |
| give examples of where background radiation can come from? | the sun- cosmic rays, hospitals, industry, nuclear explosions |
| why does radiation cause health problems? | radiation causes ionisation which leads to cells mutating which divide rapidly and can cause cancer |
| what form of radiation is more dangerous inside the body? | alpha as it cannot get out so does a lot of damage to a small area |
| what form of radiation does the most damage outside of the body? | beta and gamma as they can easily get through skin and organs quickly |
| what is nuclear fission? | splitting up a large atomic nucleus |
| what elements are often used in nuclear fission? | uranium 235 and plutonium 239 |
| how does nuclear fission work in a nuclear power station? | splitting up nucleus releases lots of heat energy, heat energy heats up water, produces steam which turns turbines to make the electricity |
| describe the process of nuclear fission | *neutron absorbed into nucleus of uranium *causes uranium to split and that releases heat and 3 neutrons *these then go on to split up more nuclei |
| what reaction happens in nuclear fission? | a chain reaction |
| how is the chain reaction controlled in nuclear fission? | control rods absorb some of the extra neutrons released stopping them splitting up more nuclei and slows down the reactions |
| why does the chain reaction in nuclear fission need to be controlled? | to avoid overheating or explosion |
| what is nuclear fusion? | the joining of two small atomic nuclei |
| what are the isotopes used in nuclear fusion? | 1 2 H and H 1 1 |
| what is the product of nuclear fusion? | 3 He 2 |
| why is fusion better than fission? | *more energy released *no radioactive waste left behind *lots of hydrogen available |
| why is nuclear fusion not yet efficient enough? | no material on earth can withstand the temperatures needed (around 10 million degrees) |
| what happened in 1989 with the scientists that claimed they achieved cold fusion? | they claimed they performed fusion at room temperatures but the results weren't reproducible |
| what cant happen in nuclear fusion and how is this avoided? | the hydrogen atoms cannot touch the sides by using a magnet |
| how is low level nuclear waste disposed of? | burying in secure landfill sites |
| how is intermediate level waste disposed of? | sealed in concrete blocks and put in steel canisters for storage |
| how is high level radioactive waste disposed of? | sealed in glass and steel, cooled for around 50 years and then moved into more permanent storage. it could then be buried but would have to be a place with no earthquakes |
| why is a fusion bomb more efficient than a fission bomb? | releases more energy |
| what is the life cycle of a smaller star? | *nebula *protostar *main sequence star *red giant *planetary nebula *white dwarf *black dwarf |
| what happens in the nebula/protostar? | *initially dust and gas *gravity makes gas and dust forming the protostar *gravity converts to heat energy and causes fusion of hydrogen to form helium *helium give out lots of heat and light and star is born |
| what happens in a main sequence star? | *massive amounts of hydrogen so lots of fusion so lots of energy *can maintain energy so can last millions or billions of years *fusion pressure provides outwards force balancing out gravity *long lasting stable period *elements as heavy as iron made through fusion |
| what happens in a red giant? | the star swells and turns red as it cools *heavier elements made by fusion of helium *hydrogen starts to run out |
| what happens in a planetary nebula? | *becomes unstable *ejects its outer layer of dust and gas |
| what happens in a white dwarf? | *a hot, solid, dense core is left |
| what happens in a black dwarf? | a cool white dwarf that eventually disappears |
| what is the life cycle of a big star? | *nebula *protostar *main sequence star *super red giant *super nova *neutron star *black hole |
| what happens with a super red giant? | *hydrogen starts to run out *heavier elements made by fusion *star swells turning red |
| what happens in a supernova? | *more fusion to glow brightly again *expand and contract several times *form elements heavier than iron and ejects them to form new planets and stars *explodes in a supernova |
| what is a neutron star? | *exploding supernova throws outer layers of dust and gas into space *leaves a dense core which is the neutron star |
| when is a black hole formed? | if the star is big enough |
| what is the 'plum pudding' model of the atom suggest? | that atoms were spheres of positive charge with electrons stuck on them |
| what did Rutherford, Marsden and Geiger's alpha particle scattering consist of? | firing alpha particles at gold foil |
| some of the alpha particles passed straight through the gold foil, what did this show? | lots of space in an atom |
| some alpha particles were deflected at small angles what does this show? | nucleus has positive charge |
| some alpha particles were deflected at very large angles what does this suggest about the nucleus? | it has a large mass and a large positive charge |
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