radioactivity Flashcards
who disproved jj thompsons plum pudding model
ernest rutherfiid
what was jj thompson model
plum pudding model
what experiment did rutherford come up with
alpha particle model
what were the three observations for rutherfords expeiment
- most alpha particles travel through the undeflected foil
- some alphaparticles are deflectd by small angles
- ## occasionally an alpha particle travels back from the foil
what is the three interprentations for rutherfords experiment
- the atom is mostly empty space
- the nucleus is postively charged as in the alpha particles
- the nucleus is where most of its mass is found
what is a neutron
subatomic particle that s of neutral charge found inside the nucleus
what is an isotope
diffrent mass number compared to other isotopes of the same element
why are some isotopes heavier than another
doffremt number of neutrons but same protons and electrons
what is an atomic number
the number of protons
what is the mass number
tells us the number of protons and neutrons
how can isotopes be represned
as a name and a number
what happens when electrons absorb energy
jump to higher energy shells.we say that the electron has become excited
what are the amount of jumps you make depent on
the energy you have
how do excitged electrons go back to lower energy shell
emits energy as electromagnetic radition
what does the amount of energy determine
wavlength of the wave
wht do emissions lines show us
the wavlenghtsof light an element can emit
what is absorption lines show us
the waveleghts of visbile light that the elemnt can absorb to becomeexicted
what hapens when the atom gains too much energy
the electron escapes the atom entirely. this changes into the positive ion
what is ionising radiation
radiation that can transfer this much energy is called ionising radiation
what is background radiation?
ionising radiation that is around us all the time from a range of sources, some of the sources and natural and some come from human activities
name diffrent sources of background raidation
- radon gas
- rocks and building materials
- medical radiation
- food
-cosmic rays
what is radon gas released frm
rock because some rocks have more uranium than others which means over time that rock will slowly be releasing radiation
why do we use medical radiation
- x rays to view broken bones
- gamma rays to diagonsoe cancer
what cosmic rays
radiation from space and most of it is filtered out from atmosphere
what is the easiest way to detect radiation
photographic film
How does photographic film detect radiation
becomes darker the more radiation reaches and the film must be developed yo measure the dose radiation
what is a dosimeter badges
use phtographic film to monitor expose to radiation and there are three layers inn it lead,allimum and paper
what causes radioactivoty
the nuclus of a radioactive substance is unstable which means it can easiy change or decay
what is decay
something breaking down
what happens when decay occurs
radiation is emitted which causes the nuceus to lose energy and become stable
how do we know when the nuceus will decay
you cannot predict, it is random
wha are gamma rays
no electric charge or mass. high frequecy em wave
what are alpha particles
two protos and two neutrons,relativ mass of 4 and charge of +2
what are positrons
high spped/energy particle. the same mass as an electron but a charge of + 1
what are beta particles
high speed/energy electrons.extremely small mass and charg of - 1
what happens when the nucleus of an atom has too many protons and neutrons
it becomes unstable and the nucleus is getting rid of them in a process called radioactive decay
if it has too many neutrons then it will be an isotopes
why are alpha particles ionsing
alpha particles are very ionsing because they havea big mass and a big chrage
how far can alpha particles travel
alpha particles can only travel only a few centimetres in air
what can alpha particlespenetrate
alpha particles can penetrate a sheet of paper but nothing thicker than that
how many types of beta partices are there
2 - beta minus and a positron
is beta plus the sameas a positron
yes
what is the mass of beta radition
1/1835
what is the charge for beta minus
-1
what is the charge for a positron
+1
what is the symbol for beta minus
B-
what is the symbol for beta plur
B+
what level of ionsing is beta radiation
both types of beta radiation are moderatley ionsng
what can beta partciles penetrate
both beta types can penetrate paper but can’t pass through allimunum
how far canbeta travel
beta can travel a few metres
what analilation
when an electron from a beta minus radiation and positron from beta plus collide and destroy each other, producing gamma rays
when does gamma radation
gamma radiation only happens after a nucleus has decayed
how far can gamma rays travel
gamma rays can travel a few kilometres through air
what level of ionsing is gamma
gamma rays are weakly ionsing in comparison to alpha and beta
what is radiation measured measured
Bequels / Bq
what is ionsing
when all these types of radiation when they meet atoms they transfer energy to the electrons in the atoms and when they have enough energy they jump to the next shell, so if they get enough energy they might completely leave the atoms. once the electrons leave the atoms, it is ionsied
what happens when an electrn isexcited
when the electrons are jumping from oneshell from another
what happens when electrons fall back into orginal shells
if an electron has been given energy and hasjumped a few shells but hasn’t completely left the atom, it will fall back into its orginal shell and will emit energy in the form of elecromagnetic radiation. this would depend on the amount of energy given
what is GM tube
sensing element of a instrument used to detect ionising radiation and is a hollow tube filed with low pressure gas
what does a counter do
you can attach the Gm tube to a counter and ot will display the count rate
what do you need to do before using a GM tube
before using a Gm tube, you need to take three measures of background radiation and find the mean background radiation
what are some possible sources of background radiation
- building
- food and drink
-cosmic rays - medical equipment
- randon gas
why ar things classified asradioactive
if the nucleus is unstable
heavy atomic nuclei that are unstable what radition do they emir
alpha radiatioon
when there is a unstable heavy nuclei alpha particles do what
help make the nuclei lighter and remove 2 protons and 2 neutrons
beta minus radiation a neutron turns into a
proton and electron is emitted
beta plus radiation a proton turns into a
neutron and a positron is emitted
whar happens to the mass number of an atom in beta minus
in beta minus the mass number of the atom won’t change
in beta minus decay why does the mass number NOT change
protons and neutrons have the same mass there is no change in the overall mass of the atom
in beta minus what happens the atomic number
in beta minus decay the atomic number increases by one
why in beta minus decay does the atomic number increases by one
because it was a neutron and that no charge at all but no it is a proton which has a charge of plus one so one is added to the atomic number
in beta plus what happens tothe mass number
in beta plus the mass number stays the same
in beta plus what happens to the atomic number
in beta plus the atomic number decreases by one
in gamma decay what happens to the mass number
in gamma decaay the mass number stays the same
in gamma decay what happens to the atomiic number
in gamma decay the atomic number stays the same
what is radioactive decay
sponatanouse provess that cannot connect be controlled and it is not effected by yempreture
what is decay rate
how fast or slow a raadiocative elemtn decays
what is half life
the time that is takes half of the unstable nuclei in the radioactive isotope to decay
what os half life measured in
a unit of time for example, seconds minits andhours
if a sample of iodine -131 has 40 undecayed nuclei,how many will be left after 8 days
40 divided by 2 = 20
in half time graphs what is the x axis
time
in half time graohs what is the y axis
acitivty or count rate
what is irradation
radation not on or in you but your just in the presence of you
what is contamination
the radioactive matriel is on or inside the body
explain the difference between nuclear irradiation and nuclear contamination
nuclear contamination is when the radioactive material is on or inside you but irradiation is when the material is just in the presence of you
what is a dosimeter badge
- monitors exposure via phtotographic film
- has layers with different absorbers
-exposure to alpha,beta or gamma can be identified
why is a benefit of getting diagnosed using gamma rays
offers diagnonsis without surgery
what is a tracer
emits gamma rays into the patient
what do tracers contain
radioactive isotopes attached to molecules that will be absorbed by particular organs.
how can tracers be administrated
injections,swallowed and inhaled
how can the tracer be detected
using a gamma camera
where are the tracers injected into
the blood
why are tracers injected into the blood
to identify the source of internal bleeding
how can tracers be used to detect tumors in gamma cameras
by making a tracer from radioactive glucose
molecules. (Cancer cells take up glucose at a faster rate than other cells).
what does PET stand for
positron emition image
In PET scans what does the tracer emit
positron
In PET scanners how does the tracer wirjs
the tracer will emit the positron a posirin and electron come togther they both destroy each other and two gamma rays are emitted in opposite direction
what does the detector in the PET scanner
builds up a set of images showingnwhere the gamma radiation is coming from.
tracer
radioactive chemical attached to a molecule
why are cancer cells dangerous
Cancer cells divide more rapidly than most other cells, which makes them more susceptible to being killed by radiation.
what is internal radiotherapy
A beta emitter is placed in the body, within or very close to a tumor.
what is external radiotherapy
Beams of gamma rays, X-rays or protons are directed at the tumor from different directions.
summaaru about using nuclear energy to produce electricity
Nuclear fuel stores a lot more energy per kilogram than other fuels antinuclear power stations are designed with many precautions.
Nuclear fuels do not emit carbon dioxide
.supplies of nuclear fuel could last a lot longer than fossil fuels.
nuclear power causes fewer death through accidents and pollution than using fossil fuels and electricity generated using nuclear energy is available at any time.
Nuclear fuel is non renewable,waste materials remain dangerous for millions of years.
it is expensive to treat nuclear waste to make it safe and nuclear power stations produce radioactive waste .
dangerous pollution from a nuclear accident can spread for thousands of kilometres,
many people are afraid of nuclear power,pollination from nuclear accidents can contamination land for decades,
nuclear power stations are much more expensive to build than fossil fuel power stations and no one wants nuclear waste to be stored near where they live.
nuclear fuels store more what
energy per kg than any other type of fuel
nuclear fuel is mon renaweable because
nucleur fuel supplies last longer
what does decommissioning
removing all fuel from a nucleur power station,taking down the plant and facillities so it can be used for something else
explain how using nucllear energy to generate electricity could be good for the enviroment
nucleur fuels do not need carbon dioxide and doesnt contribute to global warning e
what is ome pther bemnmefit of using nucleur energy to generate electricity compared to ysing fossi fuels
.supplies of nuclear fuel could last a lot longer than fossil fuels.
what is other benefit of using nucleur energy to generate electrixty compared to using wind or solar powe
nucleur is avaliable all the time and is reliable but wind and solar is dependentg on whether or time of day
whic type iof duel used to generat electricty causes the most death per billion kwh of energy produced
coal
whic type iof duel used to generat electricty causes the most death overall
coal
suggest why so many people are concerned at an aciidient in a nucleur power stattion
if an accidient happens in a nucleur power station it effects a bigger radius meaning more people
what happens to the waste in nuclur power stations
store it underground,bury it
what are the uses of radiation
smoke alarms,radioctive tracers,thickness control and sterlisation
how do radioactive tracers work
trace the path that fluid flows underground and will put a gammaradioactive substance in the fluid and there will be a higher count rate where there is a leak because the water won’t be flowing or moving on it will be just seaping into the ground
how does thickness contorl in paper
there are rollers to control paper or allimunum a beta radioactive source is above the paper and a gm tube below it and if the gm tube doesn’t detect enough radiation to it that means not many beta particles are getting through,so its gotten too thick so it sends a signal to the rollers to get closer.
how does a smoke alarm work
a radioactive substance is in the alarm,specifically americium, gives off a constant stream of alpha partciles and there is air particles in the arm,so when the alpha particles come into contact with the air particles they ionise them, the air particles now have a charge and the fact that there are charged particles moving around constantly there is a circuit and that means a current is produced , if there is smoke in the machine it will slow down or stop the alpha particles and that means the alpha particles could ionise less air particles so there will be less of the charged air particles or none at all moving across the gap in the circuit so the siren sound is set off once is falls below a certain level
how does irradaition work
to sterilise food you irradiate the food which that involves exposing the food to gamma rays that kills the bacteria and doesn’t alter the food at all or make it radioactive
what is sheilded container
lead lined container
what should you use to handle radioactive substance
tongs
what does radiation sickness cause
hair loss,vomiting and tiredness
what is the most dangeriys inside the body
alpha is the most dangerous radiation inside of the body because of it being highly ionising
what is the most dangerous outside the body
outside of the body the most dangerous is gamma and beta because it can penetrate through skin and tissue and kill organ cells
how do medical tracers work
radioactive substance, if it was gamma because it can penetrate through the body to be detected on the other side, can be injected and swallowed travels in the blood but if there is blockage or blood clot then it will get caught and stop and then lots of radiation would be detected in one place and can be detected by gamma camera
why do radioactive substances have short life when injected into the body
when radioactive substances go into the body,they have to have a short half life so that the patient wont be exposed to gamma for long periods of time
why do raduiactive substances need to be manufaturedd by the hospital
radioactive substances that are going to be used inside people’s bodies and therefore have a short half life need to be manufactured near by the hospital to insure it won’t run out during transit
how does PET scanners work
inject a patient with something that has glucose and the glucose needs to contain a positron that has a short half llfe so that the patient won’t be exposed to radiation for a long time. the glucose with the radioactive substance in it will move through the body and to the organs , the positron that is emitted with meet electrons inside the organs where anailliation when the positron will hit the electron and that means gamma rays will get emitted and because gamma rays are highly penetrate they will penetrate through the skin and be detected outside of the body. if there is a tumour the glucose would go to the tumour and the anailation that is happening will happen near the tumour and that will be the source of the gamma rays.the gamma rays that came from the analation at least three of them would be detected outsidde of the body and then triangliation would be used to find the source of the gamma rays and the source of the gamma rays will be where the tumour was
how does radation cure cancer
alpha partciles can be used and they can be injected into a tumour and because they are highly ionising they will kill the cancer cells but because they don’t got far they won’t kill things around it but you do have to stay in hospital for a long time because you might be emitting radiation and it might take several treatments of this to fully work.
external radiaotheraphy
the beam of radiation riatates around the body is focused on the tumour and does it so it only goes over healthy cells momentarily and the gamma radiation is killing the tumour and can put shield on other parts of the body but can stlll damage other parts
why do radiotheraphy sources need to have a long half life
radiotheraphy sources need to have a long half life so that they dont need to be replaced often
when sterlsing medical equipment why cant you use alpha radiatipn
alpha radiation cant be used because the equipkment will be in plastic bags and if you use it the alpha partcies cant penetrate plastic so they won’t be able to get through it and wouldn’t work
what reacction happens in a power station
nucleur fission
what is a nucleur fission
nucleur reaction that happens in a nucleur reactor
what do you need to start a nuclear fission reaction
neutron
how does nucleur fission work
parent nucleus absorbs slow moving neutrons and splits into smaller radioactive daughter nuclei, they will be much more stable than the parent nucleus but then 2 or more neutrons are released.. daughter nuclei and neutrons store large amounts of kinetic energy. Energy transferred from the fission by heating but too much heat energy can be quite dangerous
what particle triggers the nucleur fission reaction
neutron
what happens to the 2-3 neutrons that are release by nuclear fission
can be absorbed and intiate nuclear fissipn
uncontrolled nuclear chain reactions occur in what
atomic bomb
what is the fuel in a nuclear reactor made into
fuel rods
moderator
holes in a material that fuel rods are put into
control rod
contain elements that absob neutrons
what does nucleur fushion involves
light atomic nuclei fusing together to form heavier ones
what are the cinditions needed for neculear fusion
very high temperature so that the nuclei have lots of kinetic energy to move quickly which mean they are more likely to collide .
extremely high pressures which reduces the space between nucleus and brings the particles closer together to help overcome to forces of repulsion
what is the diffrence between nuckeur fiaaion and fusion
the products of nuclear fusion are not radioactive unlike fission
how does fusion work
two light nuclei collide at high speed and join to create a large heavier nucleus and the mass of the large nucleus that gets created won’t be the same as the two light nuclei that joined to create because some of the mass of the two smaller ones gets converted into energy which dissipates or is released
why does fusion onlly happen at high temperatures
fusion only happens at high temperatures because the nuclei are positively charged because they both have protons and because they are positively charged they repel each other to overcome the high electrostatic charges between them
how do you control nucleur fission through method 1
1 method - moderator, which is a liquid through which the neutrons released from nuclear fission will move through and will slow them down so they can become slow/thermal moving neutrons that are able to go on a cause more reactions
how do you control nuclear fission through control
2 method - control rods , made of boron and they absorb excess neutrons this means that there are less neutrons that can go and cause more reactions so the rate of fission is limited which means it won’t get out of control and cause an explosion
what are fuel rods
fuell rods are what the big nucleus are on and are usually uranium 235 and this is where the fission reactions happen
pros of nuclear power
- it is reliable
- it is clean because it releases green house gases
- it can generate lots of energy
cons of nuclear power
1.public perception is very bad
2 the waste from it cant be disposed safely as it is radioactive and has a very long half life so it will be radioactive for thousands of years
3. there could be leaks and it is high cost
