P7(Radioactivity) Flashcards
What were the 3 observations from Rutherfords experiment
-Most alpha particles went straight through
-Some alpha particles were deflected at an angle
- very few 1 in 10,000 were deflected at an angle more than 90 degrees
What were the 3 conclusions from Rutherfords experiment
-Most of the space in an atom is empty
-there is some volume in an atom that is positively charged
-this positive volume is very small
What is the structure of an alpha particle
2 protons and 2 neutrons
What is the structure of a beta particle
High energy electron
What is the structure of gamma radiation
Electromagnetic wave
What is the charge of an alpha particle
Positively charged
What is the charge of a beta particle
Negatively charged
What is the charge of gamma radiation
Neutral
What is the deflection for an alpha particle
Will be deflected by electric fields by positive side
What is the deflection for a beta particle
Will be deflected by electric field by negative side
What is the deflection for gamma radiation
Won’t be deflected by electrical field
What is the ionising power for an alpha particle
Highly ionising
What is the ionising power for a beta particle
Less ionising than alpha
What is the ionising power for Gamma
Least ionising
What is the penetration power for alpha
Least penetrating only travels few cm in air
-can be stopped by paper
What is the penetration power for beta
More penetrating than Alpha travels few metres in air
-can be stopped by thin aluminium
What is the penetration power for Gamma
Infinite distance
-stopped by thick lead and concrete
What are the uses for alpha radiation
Used in smoke alarms
What are the uses for beta radiation
Used to monitor thickness of paper or thin aluminium sheets
What is the uses of Gamma radiation
Used to treat cancer and it’s used to sterilise hospital equipment
What are the differences from the plum pudding model and nuclear model
-the plum pudding model has negative electrons evenly spaced out
-the plum pudding model has a positively charged sphere
-the nuclear model has negative electrons in random orbits, orbiting the nucleus
-the nuclear model has a nucleus formed of protons and neutrons which makes the nucleus have a neutral charge
How does a smoke alarm work
-Alpha particles ionise air molecules between the charged plates
-Circuit is completed live current through the gap
-smoke particles do not get ionised
-breaks circuit and alarm sound goes off
How is the thickness of the of paper monitored by beta radiation
-For constant thickness count rate does not change
-Increased thickness count rate decreases
-decreased thickness count rate increases
-detector sends message to computer to reset the thickness
-Alpha not suitable because u will not pass through paper
-Gamma not suitable as it will pass through paper unaffected
What is an alpha particle
What happens when an atom loses an alpha particle
The atomic mass number
decreases by 4
-The proton number
decreases by 2
What is a beta particle
What happens to an atom when beta(-) decay occurs
The atomic mass number remains
the same
-The proton number
increases by 1
What is radioactivity
The process in which radioactive elements decay by giving out alpha,beta or gamma radiation
What is count rate(Activity)
Number of atoms decaying per unit time
What is the formula for count rate(Activity)
Which radioactive isotope will be most suitable for medical treatment
half life of tracer must be such that it lasts till the tests have been completed
-decay almost completely after the tests
-decay into a stable product
-least ionising so it doesn’t damage living cells
-highly penetrating enough to reach detectors
-Gamma is most suitable
What is nuclear fission
Process in which a larger unstable nucleus splits into 2 smaller and stable nucleus, 2 or 3 neutrons and a large amount of energy
Diagram of nuclear fission
What are the components of a nuclear reactor
Fuel rods- made up of fissionable material
Control rods-made up of boron absorbs neutrons to slow down the process or shut it down
Moderator-made up of heavy water
Shielding- Around the nuclear reactor made from concrete and lead, prevent leak of nuclear radiation
What is nuclear fusion
Process in which 2 smaller nuclei fuse together to form larger nucleus and large amount of energy
How does nuclear fusion work
-When 2 protons fuse together they form a Heavy hydrogen nucleus
-two more protons collide with the heavy hydrogen nucleus turning the nuclei into heavier nuclei
-the 2 heavier nuclei collide to form the helium nucleus
What are the advantages of nuclear fusion
-large amounts of energy produced
-no harmful gases produced
-hydrogen is a raw material is abundant
-no nuclear waste produced
-byproduct is helium gas which is unreactive
What is disadvantages of nuclear fusion
-Technology is still in early stages of development
-energy to extract hydrogen may be taken from fossil fuels
-large amounts of energy is needed to initially start nuclear fusion
Comparing fission with fusion
Fission:
-larger nucleus splits into 2 smaller stable nuclei
-2 or 3 neutrons are produced
-energy released in form of gamma radiation
-a slow moving neutron hits unstable nucleus
-nuclear waste is produced
-technology is well known
Fusion:
-2 smaller nuclei fuse to form larger nucleus
-no neutron produced
-energy released in form of gamma radiation
-large amounts of initial energy is needed
-no nuclear waste produced
-technology is in early stages
How does nuclear fission work
a slow moving neutron hits a large unstable nucleus
-larger nucleus splits into 2 smaller stable nuclei
-2 or 3 neutrons are produced
-chain reaction is created as the neutrons emitted hit other unstable nuclei
-energy released in form of gamma radiation
