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Flashcards do conjunto (85)
- 1what is nuclear radiation?nuclear radiation is nuclear particles emitted by a radioactive nucleus
- 2what is the symbol of a proton neutron electronthe electrons mass is rounded to zero
- 3what does the structure of an atom containan electron, proton and a neutron
- 4what mass and charge does an electron have? what mass and charge does a proton have? what mass and charge does a neutron have?electron = charge -1 mass 0
proton = charge +1 mass 1
neutron =charge 0 mass 1 - 5what does the atomic number do hint it is the bottom numberit tells you the number of electrons and protons
- 6what does the atomic number do hint it is the bottom numberthe atomic number is the number of protons found in the atom
- 7what is the symbol for the atomic numberit is a z with a line through it or just a z
- 8what does the mass number do hint top numberit is atomic number+number of neutrons OR
number of protons+number of neutrons - 9what is the mass numberthe mass number is the total number of protons and neutrons
- 10what is the symbol of the mass numberA
- 11name three different kinds of radiationalpha
beta
gamma - 12what is an alpha particlean alpha particle is made of 2 neutrons and 2 protons bound together ( just like a helium atom)
- 13what is the symbol for an alpha particleit is a letter a of sorts
- 14what is an alpha particle likea helium atom as its mass is also 4 and its atomic number is also 2
- 15how is an alpha particle formedan alpha particle is formed when an unstable nucleus ejects one during an alpha decay
- 16how fast is an alpha particle7x10 to the power of 6
(7,000,000 metres per second) - 17what happens when an alpha particle is ejected2 neutrons and 2 protons are ejected
- 18what is a beta particlea fast moving electron
- 19what is the symbol for a beta particle
- 20what is a beta particle likea fast moving electron
- 21how is a beta particle formedthey are produced when a neutron in an unstable nucleus decays into a proton and electron
- 22how fast do beta particles travel atthey travel at 90% of the speed of light (2.7x10 to the 8 which is 2,700,000,000)
- 23what happens when a beta particle is ejectedan electron is released as the beta particle knocks out an orbiting electron and to stabilize a proton becomes a neutron
- 24what is a gamma raya gamma ray is a wave of energy with an extremely high frequency.
- 25what is the symbol of Gammathe gamma symbol is like an upside down ribbon
- 26how is a gamma ray formeda gamma ray is formed when an unstable nucleus releases a ray of energy
- 27how fast is a gamma raythe speed of light 3x10 to the 8 (300,000,000)
- 28what happens when a gamma ray is ejecteda wave of high energy is released
- 29what is an atom?an atom is the smallest possible of the element it makes up
- 30an element is made of?indentical atoms
- 31what do atoms have at their centres?a nucleus
- 32what does the nucleus contain?protons and neutrons
- 33does the nucleus have an overall positive or negative chargepositive as there is protons (+) and neutrons which is neutral
- 34what is ionisationionisation is when an atom gains or loses an electron to stabilize it
- 35what happens if an atom gains an electron?it becomes a negative ion
this is due to the fact that there is less positively charged protons - 36what happens when an atom loses an electronit becomes a positive ion
this is due to the fact that there is less negatively charged electrons - 37what is a protona proton is a positively charged particle
- 38what is a neutrona neutron is a neutrally charged particle
- 39what is an electrona negatively charged particle
- 40some atoms have an unstable what?unstable nuclei and can disintegrate to form the nucleus of a different, more stable atom
RADIOACTIVE SUBSTANCES ARE UNSTABLE! - 41to become more stable the unstable nuclei releases whatradiation
this process is called radioactive decay - 42ionising radiation is whationising radiation is the name given to alpha, beta and gamma radiation
this is because they produce ionisation in the material they pass through - 43what causes the most ionisation gamma, beta or alphaalpha
- 44what happens when the radiation(alpha,beta,gamma) passes through a material and collides with the atoms of the materialthey lose energy
- 45what can absorb gamma rays what can absorb beta particles what can absorb alpha particles
- 46what is absorptionabsorption is when a material absorbs the radiation
- 47alpha particles are the easiest absorbed true or falsetrue
- 48how do you detect radiationyou detect the ionisation it gives off
- 49what is the most common way of detecting radiationa geiger muller tube (GM tube)
- 50how does a GM tube worka GM tube works when the radiation enters the tube through the thin mica window, it causes ionisation in the gas
- 51what is a film badgea film badge is a piece of photographic film is covered by various thicknesses and types of absorber
- 52what is scintillationscintillation is when a fluorescent substance absorbs energy of the radiation and emits it as flashes of light
scintillations can be observed by the eye or counted using a light detector and an electronic counter - 53what is activityactivity is the "number of nuclei in a sample that decay within a given time."
- 54radiation comes from a source because?of the radioactive atoms breaking up
- 55what is activity measured inbecquerels (Bq)
- 56one becquerel is equal toone decay per second
- 571Bq=1 becquerel1 becquerel
- 58what is background radiationbackground radiation is when there is radiation in the background (these levels vary for example as there is an open cast mine near milngavie the background is higher than in say manchester or somewhere like it)
- 59what is half lifethe half life of a radioactive source is the time taken for it's activity to half
- 60what is half life measured intime; this could be seconds, minutes, hours, days even years depending on the source
- 61how to measure half lifeto measure half life you taking
measurements of the activity of the source at regular time intervals and using a GM tube, SUBTRACT background activity - 62if the activity of a source is initially 20 MBq, after 24 hours is measured as 2.5 MBq calculate the half life20 MBq=10 MBq=5 MBq=2.5 MBq
(= is 1 half life)
answer is 3 half lives
3 half lives = 24 hours
24/3 = 1 half life= 8 hours - 63how to protect against radiation three simple stepsdistance; the further away the better
time; limit the length of time spent dealing with the source
shielding; use an appropriate type and thickness of absorber to shield the radiation - 64name 3 safety stepsalways use forceps/tongs to lift a source
never look directly at the source
store in a labelled, locked, shielding container - 65name 2 things radiation can be used forsmoke alarms; work by smoke ionizing gases in the alarm completing a circuit and sounding the alarm.uses americium-147. Carbon dating; uses carbon-14 to date the age of an item by the amount of carbon in it (takes 5370 years to decay by half)
- 66name 2 other uses for radiationradiotherapy; a beam of gamma rays are fired at the cancerous cell to kill them, this has to be carefully planned as there is nearby cells to think about.
sterilisation uses UV and gamma rays to sterilise dental tools and some foods. - 67what is the corrected count ratethe corrected count rate is the count rate of a source once the background radiation is taken away from
- 68name some short term effects of radiationsevere damage to cells all over body (especially in skin,blood,bone tissue and gut)
large sudden dose of radiation - 69name some long term effects of exposure to radiationuranium miners tended to get lung cancer
people who painted luminous dials on clocks get bone cancer because they used to use their lips to make points on the brushes - 70what can affect the biological effect of radiationthe greater the absorbed dose, the greater the biological risk
the type of radiation, each type of radiation has a weighing factor, alpha particles do about 20x more damage than x-rays of the same energy. this is because alpha particles have more ionisation than beta or gamma - 71what can affect the biological effect of radiation (continued)finally the biological effect for a particular radiation is different for different types of cells exposed
some tissues in the body are more affected by the exposure to radiation than others - 72what is dosimetrydosimetry is the measurement of the absorbed dose delivered by ionizing radiation
- 73what is absorbed doseabsorbed dose is
The greater the transfer of radiation energy to the body, the greater the chance of damage to the body. The absorbed dose, D, is the energy absorbed per unit mass of the absorbing material and is measured in grays,Gy.1 Gy=1J/KG - 74what is the formula for absorbed doseabsorbed dose = energy/mass
d = E/m - 75what is nuclear fissionnuclear fission is a chain reaction when the additional neutrons released may go onto hit another nuclei and cause them to split. Even more neutrons are then released which in turn can split more nuclei
- 76what are fuel rodsfuel rods are a rod-shaped fuel element in a nuclear reactor.
the most common rods are uranium-235 and plutonium-239 these fuels are mined,refined,purified and made into fuel rods. the fuel is usually based on the metal oxide, uranium oxide for example. - 77what are fuel rods continuedthe oxides are used rather than the metals themselves because oxide melting point is much higher than that of the metal and because it cannot burn
- 78what is the moderatorthe moderator is a part of the reactor that has to slow down the neutrons in the reactor so they can cause more nuclear fission
- 79what are control rodscontrol rods are used to control the rate of fission in the reactor. they're made of chemical elements capable of absorbing many neutrons without fissioning themselves (boron,silver,indium and cadmium)
- 80what is a coolant and what does it doa coolant is a substance like water or liquid metal that is used to cool the reactor
- 81what is nuclear wastenuclear waste is the waste left over from the usage of the fuel rods
- 82what happens to the wasteit is highly radioactive and will remain so for 1000's of years. it is kept in water for several years, water being an excellent shield. Until the radioactivity decays that it can be kept in thick concrete storage casks then the final stage is a hot topic options include deep geological pits
- 83what is nuclear fusionnuclear fission is the joining of smaller nuclei to form a larger nucleus
- 84name some benefits of nuclear fusionit doesn't produce waste, in plentiful supply, would solve worlds energy problems
- 85what are some problems and down sideson earth it is difficult to create a reaction that releases more than is needed to start the reaction. Another problem is that the conditions required are close to impossible at the moment
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- FlashCards sobre Sem título, criado por Daniel McLaren em 14-02-2015.
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