P5 - Radioactivity Flashcards
What did Dalton believe about the atom
Everything was made up of solid balls, with different balls for different elements
What did Thomson discover about the atom
The existence of electrons
What did Rutherford discover
Suggested the idea of a positive nucleus, and believed the negative charge surrounded the nucleus
What did Bohr discover
That electrons orbit the nucleus, and are held in shells
How did Rutherford discover the nucleus
Fired alpha particles at a sheet of gold
What number is on top of the element symbol (physics)
Mass number
Where is the atomic number (in physics)
On the bottom
Same number of electrons as
Protons
What can happen to unstable isotopes
They can decay into other elements
What are alpha particles made up of
2 protons and 2 neutrons
What is the overall charge of an alpha particle
2+
Why are alpha particles easily absorbed
Because they are so large, they are easily stopped by collisions with other molecules
Are alpha particles strongly ionising
Yes
What are beta particles made from
An electron
What is the charge of a beta particle
-1
How are beta particles formed
When a nucleus decays into a proton and an electron
Why do beta particles penetrate moderately far into materials
because they are so small
How ionising are beta particles
Moderately
What would stop a beta particle
5mm of aluminium
What does it mean if an object is radioactive
It contains unstable isotopes
What are the 4 types of radiation emmited by an isotope
Alpha, Beta, Gamma, and the emission of a neutron
What is gamma radiation
Electromagnetic waves
Why is gamma radiation weakly ionising
Because it has no mass or charge
How far can gamma rays travel
thick sheets of lead needed to stop them
What is the emission of a neutron
If a nucleus has too many neutrons, it can emit a neutron to stabilize
How do you write an alpha particle (for a nuclear equation)
4
He
2
What does a isotope lose if it emits an alpha particle
4 from the mass number
2 from the atomic number
What is a nuclear equation for alpha decay
Old element (+ mass and atomic no.) —–> He (4 , 2) + New element (-4 from mass - 2 from atomic)
What is beta decay
Involves a neutron turning into a proton and emitting a fast moving electron
What is the nuclear equation for beta decay
Element —> New element (plus 1 atomic number) + electron
What gets added to the atom when beta decay occurs
Atomic number adds 1, as a proton has been made
How do u write an electron for beta decay formula
0
e
-1
What gets added in gamma radiation formula
Fancy Y, nothing else
What gets added in the equation for neutron emission
1 gets removed from the mass number, and the atomic number stays the same
What is neutron emission equation
Element —> same element-1mass + neutron
Can the decay of any given isotope be predicted?
No, it is completely random
What is the activity of a sample
The overall rate of decay
What is a Becquerel a measurement of
Radioactive decay
What is the symbol for Becquerels
Bq
What is 1 Bq
1 decaying isotope per second
What is half life
Time taken for number of radioactive isotopes in a sample to halve
Time taken for activity of a sample to halve
Why does activity decrease the more nuclei decay?
Because there are less remaining nuclei to decay, so the process slows
How do u calculate the half life on a activity, time graph
Work out how long it took for the activity to halve
How do you find the activity of a sample
Use a geiger counter
How do geiger counters calculate the activity of a sample
They record all the decays that reach them per second
What is the count rate
The amount of decays a geiger counter receives per second
What does irradiation mean
The process by which objects are exposed to any type of radiation (ionising or non)
What is contamination
When radioactive particles get on the surface of other objects.
Why can contamination be dangerous
Because if the particles decay, you can be subjected to harmful radiation
What 3 factors determine the danger of radiation
Type of radiation
Location on body of exposure
Amount of radiation you receive
Why is ionising radiation dangerous
Because it can ionise your DNA and cause mutation or cancer
What is the only non-ionising radiation that can cause cancer
Ultraviolent radiation
If the source is outside the body, what is the order of danger in radioactive particles
Beta, (most)
Gamma,
Alpha (least)
If the source is on or in the body, what is the order of danger in radioactive particles
Alpha, (most)
Beta,
Gamma (least)
What is the amount of radiation received called
Dosage
What 3 factors can reduce the dosage of radiation
Distance from source
Length of exposure
Radioactivity of sourcef
How can you protect against dangers caused by radiation
Wear protective gear
Handle substances with tongs
Keep substance in lead lined box
What can happen to cells if they receive a large enough dosage of radiation
Cells can be killed
What causes radiation sickness
Large scale death of cells, caused by radiation exposure
What are some symptoms of radiation sickness
Hair loss,
Vomiting,
Tiredness
What two ways can radiation be used to kill cancer cells
Externally or Internally
What is external cancer treatment
Gamma rays target cancer site, from many different angles
What is internal cancer treatment
Radioactive source is placed inside the body, either in or next to the cancer source.
What type of radiation is used for internal cancer treatement
Beta particles
What is a medial tracer
Placing a radioactive isotope in a person’s body by ingestion or injection, we can track its movement and check if particular organs are working properly.
What type of radiation is used in medical tracers
Gamma, as it is the least harmful
What kind of half life do the isotopes used in medical tracers have
The shortest possible, only emitting radiation while they are being measured
What is nuclear fission
The splitting of a large, unstable nuclei
What are the 2 types of fission
Spontaneous fission, and fission by absorbing a neutron
What is spontaneous fission
Fission which happens by itself, unforced
Which type of fission is rare
Spontaneous fission
What is the other type of fission
Absorbing a neutron into an atom makes it even more unstable, which gets the process of fission started
What is the process of fission (chain reaction)
Fire a slow moving nuclei at a large unstable isotope, which makes it more unstable, and causes it to split into 2 daughter nuclei, as well as releasing a few more neutrons and LOTS of energy in the form of gamma radiation. These neutrons then hit more isotopes and repeat the process of fission.
What type of energy is given off during fission
Gamma radiation
Symbol for neutron
n
What does nuclear fission lead to
A chain reaction
What can happen if fission is not controlled
It can quickly get out of hand and release massive amounts of energy
How can you control the rate of fission in a nuclear power plant
By lowering control rods into the reactors, which absorb neutrons and therefore slow the fission down
What are the pros of nuclear power
Cheap fuel,
Clean and steady energy
What are the cons of nuclear power
Power stations are pricey to build
Nuclear waste is expensive to dispose of
What is fusion
2 light nuclei fuse to make one single larger nuclei.
What process fuels stars
Nuclear fusion
Why does fusion produce so much energy
Because during the process, some mass is lost from the nuclei (source: trust me bro) and E = MC^2 means lots of energy is released
How are all elements heavier than hydrogen made
Fusion
What is good about fusion
it makes NO nuclear waste, and hydrogen (the fuel) is very easy to access
What is the issue with fusion
It needs 10,000,000 degrees celsius of heat, and lots of pressure, so it is not yet possible on earth
What releases more energy per mass of fuel fission or fusion
fusion produces much more
What is the size of an atom
1x10^-10 m
