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Atomic structure - physics topic four
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- 1What was the plum pudding model?The first atomic model of the atom which suggested atoms were spheres of positive charge with tiny negative electrons stuck in them, like a plum pudding
- 2What is the radius of an atom?1 x 10^-10 m
- 3What is an isotope?Different forms of the same element with the same number of protons and electrons but a different number of neutrons.
- 4What is the mass number of an atom?The number of protons + neutrons in its nucleus
- 5What are unstable isotopes?Isotopes that decay into other elements and five out radiation as they try to become more stable.
- 6What is the process of decaying isotopes called?Radioactive decay
- 7Name the three main forms of ionising radiationAlpha, beta and gamma
- 8What is an ionising radiation?A radiation that knocks electrons off atoms, creating positive ions
- 9What is ionising power?How easily a source of radiation can carry out ionising radiation
- 10What is an alpha particle made up of?Two neutrons and two protons, like a helium nucleus
- 11How ionising are alpha particles?Not very strong, they don’t penetrate far into materials and can be absorbed by a sheet of paper. However because of their size they are strongly ionising
- 12What makes up a beta particle?A single fast moving electron
- 13How ionising are beta particles?Moderately ionising, they penetrate reasonably far into materials and can be absorbed by a sheet of aluminium.
- 14What makes up a gamma ray?Waves of electromagnetic radiation
- 15How ionising are gamma rays?They penetrate far into materials and can travel a long distance through air. This means they are weakly ionising because they pass through rather than collide with atoms. They can be stopped with lead or metres of concrete
- 16How are nuclear equations written?Atom before decay = atom after decay + radiation emitted
- 17What is the one rule to remember about nuclear equationsThe total mass and atomic numbers must be equal on both sides
- 18How can radiation be measured?With a Geiger muller tube and counter
- 19What is half life?The amount of time it takes for the amount of radioactive nuclei emitted by a source to halve
- 20What is activity measured in?Becquerels, Bq (one Bq is one decay per second)
- 21What is background radiation?The low levels of radiation around us at all times. It must always be subtracted from calculations when measuring increases in radiation.
- 22Name the three sources of background radiationNaturally occurring unstable isotopes, the sun (cosmic rays) and radiation due to human activity
- 23what is exposure to radiation called?irradiation
- 24name three ways of reducing the effects of irradiationkeeping sources in lead boxes, standing behind barriers and using robotic arms from a separate room
- 25what is contamination?when unwanted radioactive atoms get transferred to an object
- 26what precautions can be taken against radioactive particles?wearing gloves and using tongs, or wearing protective suits and masks
- 27which two forms of radiation are the most dangerous outside the body?beta and gamma because they can penetrate the body and get into the organs
- 28which source of radiation is the most harmful inside the body?alpha because they do all their damage in a very localised area, beta and gamma are not as damaging
- 29name three health issues radiation can cause?tissue damage, cancer and radiation sickness
- 30how can iodine 123 be used medically?it can be injected into a patient to test of their thyroid gland is working properly
- 31How can radiotherapy be used to treat cancer?Gamma rays are directed carefully at the cancer cells , or beta emitting implants are placed next to tumours. It still damages a large number of normal cells which makes the patient feel very ill
- 32Why would some patients not want to be diagnosed with a medical tracer?Tracers can cause cancer on rare occasions
- 33What is nuclear fission?Nuclear fission is a type of nuclear reaction that is used to release energy from large unstable atoms by splitting them into smaller atoms
- 34What is released during nuclear fission?The large unstable atom splits into two smaller atoms roughly the same size and a few neutrons are also released
- 35How is energy produced from nuclear fission?It is carried away on gamma rays
- 36How is the speed of nuclear fission changed?Control rods are lowered and raised inside the nuclear reactor to absorb neutrons and control the energy output
- 37What is nuclear fusion?When two light nuclei collide at a high speed and join to create a larger heavier nucleus
- 38Why haven’t scientists found a way of using fusion yet?The temperatures and pressures needed are so high that fusion reactors are extremely expensive and hard to build
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- GCSE Physics Fichas sobre Atomic structure - physics topic four, creado por rosie holgate el 11/11/2018.
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- rosie holgate
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