P7-Radiation Flashcards
What is alpha radiation
Alpha radiation is where alpha particles are emmited from a nucleus
What is the structure of an alpha particle
Alpha particles have the same structure as a helium nucleus (2 protons,2 neutrons)
How penetrative are alpha particles
Alpha particles are not very penetrative and can travel through only a few mm of air before being stopped. They can also be absorbed by paper
How ionising are alpha particles
Alpha particles are the most ionising type of radiation , mostly because of their size, and can cause the most damage
What is beta radiation
Beta radiation is when beta particles are emmited from a nucleus
What are Beta Particles
Beta particles are very fast moving electrons. They have a charge of -1 and a very small mass
How ionising and penetrative are beta particles
Beta particles are moderatly ionising
Beta particles are moderatly penetrative as they can travel through metres of air but only mm of alumium
What do beta particles do when they collide with atoms
When beta particles collide with atoms they cause neutrons to become protons. This increases the number of protons in the atom but the overall mass number stays the same (as there are still the same amount of neutrons and protons combined). This also causes the positive charge of the nucleus to increase
What are gamma rays
Gamma rays are waves of electromagnetic radiation emmited from the nucleus
How penetrative are gamma rays
Gamma rays are very penetrative and can travel long distances through air without being stopped. They can be stopped by lead or concrete
How ionising are gamma rays
Gamma rays mainly pass through atoms rather than colliding with them so are less ionising than beta and alpha particles
What is the general formula for nuclear equations
The general formula for nuclear equations is
Atom before decay —> atom after decay + radiation emmited
What is the key rule for nuclear equations
The key rule for nuclear equations is that the atomic number before and after the decay must be the same (after =after+radiation emitted)
How does that atom after the decay change when an alpha particle is emmited
- When an alpha particle is emmited from the nucleus the atom after the decay has 2 less neutrons and two less protons than before the decay
- This means the mass number reduces by 4 and the atomic number by 2 from the atom before decay
How does the atom after decay change after a beta particle is emmited
- When a beta particle is emmited one of the nuetrons from the atom before the decay turns into a proton for the atom after decay
- This increases the atomic number of the atom after decay by 1 as there is one more proton but the mass number stays the same as there are still the same amount of total protons and nuetrons
How does the atom after decay change after a gamma ray is emmited from the nucleus
- Gamma rays are used by the nucleus to get rid of excess energy from it
- They have no affect on the atomic number or mass number
What is half life
Half life is the time it takes for the number of radioactive nuclei in an isotope to half
What can half life be used to figure out
Half life can be used to figure out the rate at which a radioactive source decays -the activity
What does a short half life mean
A short half life means that a sources activity falls very quickly and that the radioactive isotope is very unstavle and decays rapidly
What does a long half life mean
A long half life means the activity falls more slowly as most of the nuclie dont decay for a long time . This can be dangerous over a long time period
What are the risks of radiation
- Radiation can enter living cells and ionise the atoms and molecules within them , leading to tissue damage
- Lower doses can lead to mutated cells which can lead to their uncotrollable divide and growth ,forming tumours
- Higher doses of radiation can lead to complete killing of cells , leading to radiation sinkness
What are the uses of radiation
- Since high doses of radiation can kill all cells radiation can be used to kill cancerous cells
- gamma rays are carefully directed just at the right doses at cancerous cells , which kills them without killing too many normal cells
How frequent is radioactive decay
Radioactive decay is random
What else can radioactive isotopes be used for
Radioactive iosotopes can also be used for checking blocked kidneys.To do this a small amount of iodine 123 is injected into the patient and read from outside from a gieger counter. If the kidney is blocked it will stay emmiting radiation for a prolonged period of time and the count rate will stay high
What is nuclear fission
Nuclear fission is the splitting of an unstable atomic nuclei it requires a lot of energy
What does an atomic nucleus require to split
For a split to hapoen , a neutron needs to be absorbed into an atomic nucleus
What does the atomic nuclie split into
The atomic nuclie splits into two smaller nuclie of roughly the sams size. They have energy in their kinetic energy stores
What is also released when a nuclie splits
When a nuclie splits two or three neutrons are also released. If they are moving slow enough to be absorbed by another nucleus more fission occurs and a chain reaction is started
What can the energy released during nuclear fission be used for
- Lots of energy is released during nuclear fission as gamma rays
- This energy and the energy in the kinetic energy stores of the products can be used to heat water to make steam to turn a generator to produce electricity
Why do nuclear reactions have to be controlled
Nuclear reactions have to be controlled as if they are not too much energy will be released and an explosion will occur
How are nuclear reactions controlled
Nuclear reactions are controlled using control rods that absorb surplus neutrons and stop great chain reactions happening. By stopping chain reactions they stop too much energy being released which can cause an explosion
What happens during nuclear fusion
During nuclear fusion two lighter nuclie collide at high speeds to form one ,larger heavier nucleus.
The heavier nucleus doesnt have the same mass as the two lighter nuclei as some energy is also released
What are the sources of background radiation
Background radition comes from many sources
- It comes from naturally occuring unstable isotopes e.g rocks and food
- It comes from space in the form of cosmic rays
- It comes from human activity such as nuclear waste and nuclear explosions
What is irradiation
- Irradiation is when an object is exposed to a radioactive source (when an object is near a radioactive source)
- It does not make the object itself radioactive
What is contamination
Contamination is when an unwanted radioactive element gets into or onto an object
Why can contamination be harmful to human health
Contamination can be harmful as the radioactive element could decay releasing radiation harmful to human health
-This radiation could ionise cells within the body which could lead to mutations
Which types of radiation are the risks of irradiation highest with
The risks of irradiation are highest with beta and gamma particles as these two are the most penetrative so can penatrate through skin cells.
What is the most harmful type of radiation with contamination
Alpha radiation is the most harmful type of radiation with contamination as it is the most ionising type of radiation and causes lots of localised damage
Why is iodine used as a tracer in the body
- Iodine has a half life of 8 days so it lasts long enough for the tests but decays almost completlety after
- Iodine emmits gamma rays so can be detected outside the body
- Iodine decays into a stable product
What direction will an alpha particle deflect in an a electrical field
In an electrical field the alpha particle will deflect towards the negative side of the electric field due to the fact that the alpha particles have a positive charge
What direction will a beta partivle deflect in an electric field
A beta particle will deflect towards the positive end of the electric field as the beta particle has a negative charge
What is another definition for half life
The half life is the time it takesfor the count rate from a sample containing the isotope to fall to half its initial level
