Nuclear Physics Flashcards
What is the mass number?
Number of protons and neutrons in the nucleus
What is the atomic number?
Number of protons/electrons in an atom
What are isotopes?
Are atoms of the same element which have a different mass number
What does 23Na stand for?
23 is the mass number
Give an example of natural nuclear reaction
Nuclear decay
Define nuclear decay
It is the process where part of unstable nuclei disintegrated from it and it is emitted as radiation
Give examples of artificial nuclear reactions
Fusion and fission
Define nuclear fusion
It is the process where two atomic nuclei combine
Define fission
It is the process where atomic nucleus splits to other fragments
How is radioactivity measured?
In becquerels
In alpha decay what happens to the atomic number and mass number?
Mass number decreases by four
Atomic number decreases by 2
What is produced in alpha decay?
Helium
What is radioactivity?
A random process
What is background radiation?
The low intensity present in the Earth’s atmosphere.
Give sources of background radiation
Radiation from the earth's crust Radiation from outer space Emission from nuclear experiments and power stations Building materials Radon gas
How does radioactivity form ions?
When alpha, beta particles or gamma rays collide with a material they knock off an electron
What is an ion?
Any atom that has lost or gained electrons
What are uses of ionising radiation?
A smoke detector
What is the relative charge of alpha particles?
+2
What is the speed of alpha?
0.1 speed of light
What is the ionizing effect of alpha particles?
Highest ionisation due to frequent collision with gas molecules since they are massive
What is the penetrating effect of alpha particles?
Stopped by a sheet of paper or skin
What are beta particles?
High energy electrons emitted from the nucleus
What is the relative charge of beta particles?
-1
What is the ionising effect of beta particles?
Much less ionisation than alpha rays
What is the penetrating effect of beta particles?
Stopped by a few mm of aluminium
What is gamma rays?
High energy-frequency electromagnetic radiation
What is the relative charge of gamma rays?
0
What is the ionising effect of gamma rays?
least ionisation effect
What is the speed of gamma rays?
Speed of light
What is the penetrating effect of gamma rays?
Very high penetration effect can only be stopped by a thick sheet of lead
When the current is going down( positive is up, negative is down) what happens when alpha particles are being shot through it?
They will be slightly deflected down
When the current is going down( positive is up, negative is down) what happens when beta particles are being shot through it?
They are deflected more up
When the current is going down( positive is up, negative is down) what happens when gamma rays are being shot through it?
Nothing happens
When the current is going up( positive is down, negative is up) what happens when alpha particles are being shot through it?
They will slightly deflect up
When the current is going up( positive is down, negative is up) what happens when beta particles are being shot through it?
They are deflected greatly down
What happens in beta radiation?
A neutron in the parent nucleus changes to proton and electron
What happens to the mass number and atomic number in beta decay?
The atomic number increases by one
What is the half life?
Average time for half of the atoms in a given sample to be decayed or average count rate reduced to half of the original counts
What happens in a graph showing count rate?
It decreases
What is decay series?
It is one element turning into another which turns into another
What are uses of radioactivity?
- Gamma rays are used to kill bacteria- sterilization
- Smoke detector
- Monitor thickness
- Carbon dating- find the age of living organisms
- Dating rocks
- Find leaks/blockages in pipes
- Tracers to investigate a patient’s body
- Treatment of cancer
Which radiation is the most dangerous if the radioactive source is inside the body?
Alpha radiation because it is easily absorbed by cells
Which radiation is the most dangerous if the radioactive source is outside the body?
Beta and gamma because they can penetrate through skin
