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physics 1.4
Fichas del conjunto (38)
- 1describe the plum pudding modelJ.J. Thompson created the theory that atoms were positive spheres containing tiny negative electrons
- 2what happened to change the plum pudding theory in 1909Rutherford's alpha particle scattering experiment
- 3what was the alpha scattering experiment and what were the resultsRutherford fired tiny gold alpha particles at thin gold foil, most went through, some didnt
- 4what did the alpha scattering experiment tell usmost of the mass in an atom was in the centre and was positive as some reflected, also atoms are mostly empty matter as most went through
- 5what did the alpha scattering experiment lead tothe nuclear model
- 6what did Neils Bohr discoverelectrons orbited the nucleus at a distance
- 7what did James Chadwick discoverthe neutron, which explained the imbalance of atomic and mass number
- 8what does the current model of the atom look likehas a nucleus which contains neutrons and protons which is positive, electrons orbit in shells around the nucleus
- 9what is the mass number of an atomnumber of protons + number of neutrons
- 10what is the atomic number of an atomnumber of protons or number of electrons
- 11what is an isotopean element with the same number of protons and electrons but a different number of neutrons
- 12what is radioactive decaywhen an isotope decays into other elements and gives off radiation
- 13what is an alpha particle made of2 neutrons and 2 protons
- 14what are the properties of alpha particlesstopped quickly, don't penetrate very far into materials, only travel a few cm in air, absorbed by paper, strongly ionising
- 15what is a Beta particlea fast moving electron released from the nucleus
- 16what are the properties of a Beta particleno mass, negative charge, moderately ionising, penetrate moderately far into materials, range in air of a few metres, absorbed by aluminium
- 17for every Beta particle emitted, what is turned into whata neutron is turned into a proton
- 18where are gamma rays emittedthe nucleus
- 19what are the properties of gamma rayspenetrate far into materials, long distances through air, weakly ionising, absorbed by thick lead or concrete
- 20how do gamma rays affect mass and atomic numbers of an atomthey don't
- 21what is the definition of half lifethe time taken for the number of radioactive nuclei in an isotope to half
- 22why is half life usefulradioactive decay in nuclei is entirely random so you cant predict wat will decay next so half life gives us a rate at which the nuclei decay
- 23what is background radiationthe low level radiation which is around us all the time
- 24where does background radiation come from (examples)naturally occurring unstable isotopes, cosmic rays, human activity like nuclear waste
- 25what is irradiationexposure to radiation
- 26what are ways of reducing the effects of irradiationkeeping sources in lead-lined boxes, standing behind barriers, wearing a lead apron etc
- 27what is contaminationunwanted radioactive atoms come into contact with an object
- 28true or false - contamination is harmless and irradiation is harmfulfalse - other way around
- 29how is contamination preventedwearing gloves, using tongs, wearing a protective suit
- 30what is the most harmful sources of radiation outnside the bodybeta and gamma as they can penetrate the skin and get to delicate organs
- 31what is the most harmful source of radiation inside the bodyalpha as they do the damage in very localised areas
- 32what are the risks of using radiationionise atoms and molecules in cells which can lead to tissue damage, lower doses can result in mutating cells which is cancer, higher doses kill cells completely which leads to radiation sickness
- 33how is a gamma source used as a medical tracer and why gammait can be injected or swallowed and then it can be followed through the body, short half life and it is not very ionising (usually just pass straight out after)
- 34explain radiotherapy and the risksgamma rays are pointed at the target cancer cells and are killed off, can do some damage to other cells and can make the patient very ill
- 35summarise nuclear fission as a wholea neutron is fired at an atom to release two new lighter atoms and 3 neutrons which then fire at other atoms and start a chain reaction, lots of energy is released so it can be used to provide energy for large scale things such as generators, uncontrollable fission causes an explosion (how nuclear weapons work)
- 36summarise nuclear fusion as a wholetwo light nuclei collide at a high speed and join to form a heavy nucleus, some energy is released as radiation, fusion reactors are expensive and hard to build
- 37what releases more energy - nuclear fusion or fissionfusion (but we don't know how to use it yet)
- 38true or false - fission is usually spontaneousfalse
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- Physics Fichas sobre physics 1.4, creado por Olivia Harlington el 25/03/2019.
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- Olivia Harlington
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