P7 - Radioactivity Flashcards
What is nuclear radiation?
When the nucleus of an atom emits radiation because it is unstable
Why would a nucleus be unstable and emit radiation?
The nucleus has too many protons
The nucleus has too many neutrons
The nucleus is too large
What are the four types of nuclear radiation we need to know for gcse?
Alpha particles
Beta particles
Gamma rays
Neutrons
How did Ernest Rutherford decide to test JJ Thompsons plum pudding model?
He aimed alpha particles at thin gold foil to detect the alpha particles path
After Rutherford alpha particle experiment, what did he deduce?
The nucleus is where most of the mass is located
The nucleus is postively charged because it repels the alpha particle
The nucleus is much smaller than the atom because alpha particles pass through without deflection
What is the atomic structure of an alpha particle?
Made of 2 protons and 2 neutrons
What is the charge and mass of an alpha particle?
Charge of 2+
Mass of 4
How many protons + neutrons are lost when an atom emits alpha decay?
2 protons + 2 neutrons
How are Beta particles formed?
One of an atoms neutrons decay into an proton an an electron.
The proton stays in the nucleus and the electron is emitted out st high speed
We call this electron a Beta Particle
What is the charge and mass of a beta particle?
Charge of -1
Mass of 0
What is Gamma Radiation emitted by?
Unstable nuclei
Why cant alpha particles penetrate very far into other materials?
Because they are relatively large, they are easily stopped by collisions with other molecules
How far can alpha particles travel?
A few cm in air and can be absorbed by a single sheet of paper
Because Alpha particles are relatively large, they are strongly ionising. What does this mean?
They can easily knock electrons off any atoms that they collide with
Why can Beta particles penetrate moderately far into other materials?
Because they are tiny and are emitted at high speeds
How far can beta particles travel?
Several meters of air and are absorbed by 5mm of aluminium
Why are gamma rays not classified as particles?
They are waves of electromagnetic radiation
What is the charge and mass of gamma rays?
No charge and no mass
Why do gamma rays pass through materials easily?
They don’t have any mass or charge that can collide with any atoms
Are gamma rays weakly ionising?
Yes 👍
How far can gamma particles penetrate?
Long distances through air and is absorbed by thick sheets of lead
When does the emission of a neutron occur
If a nucleus is unstable because there is too many neutrons, they can just throw unneeded ones out
What is the frequency of the decay process?
It is completely random
What does the activity of a sample mean?
The overall rate of decay of all the isotopes in our sample
What is activity measured in?
Becquerels
Where 1Bq = 1 decay per second
What are the two definitions of half life?
The time taken for the number of radioactive nuclei in a sample to halve
The time taken for the number of decays or activity to halve
What is irradiation?
The process by which objects are exposed to radiation
What is contamination?
When radioactive particles get onto other objects
What determines how harmful radiation can be to humans?
The type of radiation
Where your exposed to it
The amount of radiation recieved
What type of radiation is most dangerous?
The ionising ones
Why are the ionising radiations dangerous to humans?
They enter into living cells and ionise our DNA
This leads to cells mutating uncontrollably which leads to cancer
What are two uses of radiation in medicine?
Radiotherapy
Medical tracers
What is radiotherapy?
Using radiation to destroy particular cells in our body like cancer cells
What are the two ways of delivering radiotherapy to cancer patients?
Externally and internally
How does the external treatment using radiotherapy work?
Emitting gamma rays at the cancer site from all angles
How does the internal treatment using radiotherapy work?
Placing beta particles inside the cancer
Why would professionals place beta particles inside the body instead of gamma rays?
Even though beta particles are more damaging, they cant penetrate far through the body
What are the side effects of radiotherapy in cancer patients?
It also kills healthy cells
What are medical tracers?
Tracing the movement of radioactive isotopes that are injected into people go check if organs are working properly
What is nuclear fission
The splitting up of large and unstable nuclei into smaller nuclei
What are the two ways that stimulate nuclear fission to take place?
Spontaneously or when Absorbing a neutron
Explain the process of nuclear fission.
A slow neutron is fired at a large, unstable nuclei
The additional neutron makes the nuclei even more unstable snd cause it to split apart into two daughter nuclei.
This process releases 2-3 neutrons and lots of energy.
The neutrons released repeat this process
How do nuclear reactors control the rate of nuclear fission?
Control rods in the reactor to absorb neutrons
What are the pros of nuclear energy?
Fuel is cheap
Doesn’t produce greenhouse gases
What are the cons of nuclear energy?
Power plants are very expensive to build
Nuclear waste is also hard and expensive to get rid of
Still a risk of disaster although its small
What is nuclear fusion?
When two light nuclei join or fuse to form a single large nuclei
During nuclear fusion, what is released?
A lot of energy
Why is nuclear fusion a fundamental in life?
Its how all elements heavier than hydrogen were made
Why does nuclear fusion release so much energy?
Some of the mass of the original nuclei is converted to energy rather than transferred to the new nucleus
What is the pros about nuclear fusion?
It doesn’t produce any radioactive waste
What is a con about nuclear fusion for humans?
It only occurs at extremely high temperatures and pressures (10 000 000°C) so it can not be done on earth
What are the differences between nuclear fusion and nuclear fission
Fusion is the fusing of light nuclei to make heavier nuclei | fission is where large, unstable nuclei are split into two smaller nuclei
Fusion only happens in stars | fission can happen anywhere with right conditions
Fusion produces tons of energy | fission produces lots as well but nowhere as much as fusion
Name the element that changes into radon when it decays
Radium (Ra)
