radioactivity Flashcards
What is the Rutherford experiment
He fired neutrons at gold film in order to test whether the plum-pudding model was correct
What was the outcome of the Rutherford experiment
If the plum-pudding model was correct the neutrons would have passed straight through ,however, some deflected at an angle and others were repelled
what was the plum-pudding model
Electrons with a negative charge were surrounded by a cloud of positive electric charge
What is alpha decay
The parent nucleus emits 2 protons and 2 neutrons(which is a helium nucleus)
What are the products of alpha decay
The daughter nucleus has 4 less nucleons and 2 less protons. It produces an alpha particle which has 4 nucleons and 2 protons
What is beta decay
A reaction in the parent nucleus producing an electron
what are the products of beta decay
The daughter nucleus has 1 more proton whilst the nucleons stay the same. A beta particle is produced which is just 1 electron.
what is gamma decay
an electromagnetic wave is emitted causing the nucleus to lose energy
What are the products of gamma decay
There are no changes
Alpha particle stats
mass number of 4, 2+ charge, low penetrating power and a high ionising ability, speed is slow
Beta particle stats
negligible mass number, 1- charge, moderate penetrating power and a moderate ionising ability, speed is fast
Gamma particle stats
mass number of 0, charge of 0, high penetrating power and a low ionising ability, travels at the spead of light 3x10^8 m/s
What is half life
The time taken for;
- number of radioactive nuclei to halve
- mass to halve
- activity to halve
How to measure half-life on a graph
You need an average of three intervals being exactly half of the value of the one previous to it and then measure the time taken between the three. They should take the same time to half if half life is occurring
Leak detection
They emit gamma rays due to it’s long range and high penetrating power so it can detect the leakage the best
Tracing movements
Scientists are able to know where and how fast water could be travelling when iridium-113 is injected into it at very small dosages as scientists can look at the gamma radiation given off from it.
why can beta or gamma be used in medical tracing but not alpha?
beta or gamma will pass out the body quickly, however, alpha would most likely be absorbed and is very ionising so it can be deadly
why is half life important in radioactive tracing
must be long enough to follow the investigation and yet short enough to avoid unnecessary exposure
Why is gamma radiation used in radiotherapy
Gamma is penetrating enough that it is able to enter the body to then kill the cancer cells, it is also not very ionizing so it won’t be as harmful to the body as beta or alpha
why are alpha particles not used in smoke alarms
they are not penetrating enough and are likely to be absorbed by the smoke itself
what type of radiation is used to sterilize medical equipment and food
gamma
why is gamma used to sterilize medical equipment and food
it destroys the bacteria and the energy of gamma rays passes through the equipment, disrupting the pathogens that cause contamination
why is beta used in thickness control
Beta is able to penetrate paper ,however, this penetration starts to vary as the thickness of the paper changes. It can monitor the thickness of the paper
What is nuclear fission
A neutron is slowly fired at a parent nuclei which then splits into two daughter nuclei and produces lots of energy
What is a chain reaction
Where one fission causes many more fission events which then lead to more fission events in an uncontrollable fashion
what is a turbine
A windmill like mechanism which gets turned by the steam from the reactor to generate energy
what is nuclear fusion
a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles
what is the life cycle of low and medium mass stars
nebula => main sequence => red giant => “planetary nebular” => white dwarf
what is the life cycle of high-mass stars
nebula => main sequence => red supergiant => supernova => neutron star
what is the life cycle of very high-mass stars
nebula => main sequence => red supergiant => supernova => black hole
what is the function of the control rods
used to absorb excess neutrons and prevent chain reaction
what is the function of a moderator
substance (usually water or CO2) used to absorb energy from the nuclear reactor to generate electricity
what is the function of a coolant
slows down neutrons in the reactor to ensure they are able to interact with Uranium
what is the function of the fuel rods
contains the uranium needed for the reactor
