12. P7 Radioactivity Flashcards
Name the three types of radiation given out by unstable isotopes?
Alpha Beta Gamma
What will stop alpha radiation?
Sheet of paper
What beta radiation can be stopped using?
3-5mm of Aluminium
What gamma radiation can be stopped using?
5-10 cm of lead
What is alpha radiations range in air?
up to 5cm in air
What is beta radiations range in air?
up to 1m in air
What is gamma radiations range in air?
over 1km in air
What is alpha radiation made up of?
2 protons and 2 neutrons
What is beta radiation made up of?
fast moving electron
What is gamma radiation made up of?
Energy (electromagnetic wave)
Which type of radiation is the most highly ionising?
Alpha
Which type of radiation travels at the speed of light?
Gamma
Which type of radiation is not affected by a magnetic or electric field and why?
Gamma as it does not have charge
The charge of an alpha particle?
Positive
The charge of a beta particle?
Negative
Name of scientist who discovered the electron and put forward the plum pudding model fo the atom?
JJ Thompson
What equipment did Rutherfords assistants use in order to test the plum-pudding model?
Thin gold foil, microscope with zinc sulphide screen, alpha source in lead shield with narrow opening, all within a vaccuum.
What observations were made from Rutherford’s experiment?
1) Most of the alpha particles passed straight through, 2) Few were deflected at small angles, 3) Very few were repelled at large angles(>90degrees) back in the direction of the source
What were Rutherford’s conclusion from the Alpha-scattering experiment?
1) Most of the atom is empty space, 2) Contains a small positively charged point which contains most fo the mass.
Where is all radiation emitted from
Nucleus of unstable isotope
Why did Rutherford carry out the alpha scattering experiment all within a vacuum?
So the air would not affect the path of the alpha particles. Alpha particles are easily absorbed by air and only have a range of upto 5cm.
Name given to the model of the atom which displaced Thompson’s Plum-pudding model after Rutherfords results?
Nuclear Model
Name of the scientist who adapted Rutherfords model to include the electrons orbiting around the nucleus and existing in “shells”?
Neils Bohr
Name of scientist who found direct experimental evidence for the existence of the Neutron which was found alongside protons in the nucleus?
James Chadwick
What does the atomic number of an element tell us?
The number of protons in the nucleus
What does the mass number of an element tell us?
The number of protons and neutrons in the nucleus.
What is meant by an isotope?
An element with the same number of protons but different number of neutrons.
What happens to the proton number when an unstable isotope emits an alpha particle?
Goes down by 2
What happens to the proton number when an unstable isotope emits an beta particle?
Goes up by 1
What happens to the proton number when an unstable isotope emits an gamma particle?
Stays the same
What happens inside the nucleus during beta decay?
Neutron decays into a proton, emitting an electron.
What is meant by radiation being ionising?
Can collide/interact with other atoms and remove electrons from their shells, causing the atom to become charged.
What can happen if ionisation takes place in living cells?
Cells damage (or kill it), which can lead to cell mutation and cancerous growths.
What is meant by radioactive contamination?
When a radioactive source comes in contact with another object/surface.
Which is the most dangerous type of radiation inside the body?
Alpha, as all the ionisation takes place inside the body as alpha can not pass through it.
What safety precautions should be taken when dealing with radioactive sources?
Wear the necessary protective clothing and goggles, handle using tongs(no direct contact), limit time spent handling/in same area of the radioactive source
What is the name given to the process where other scientists check the work and findings of another scientist?
Peer review
Which type of radiation emitting isotope would be used in smoke alarms?
Alpha emitting isotope
Which type of radiation emitting isotope would be used for industrial tracing like finding leakages in underground water pipes for example?
Gamma emitting isotope
Which type of radiation emitting isotope is used in production lines for controllign the thickness of aluminuim foil?
Beta emitting isotope
Explain how radiation can be used to control the thickness of the aluminium foil?
If the foil becomes too thin, more beta radiation passes through the foil so the detector detects a greater signal. This is fed back through a computer, which decreases the pressure on the rollers.
What is the unit for activity of a radioactive source?
Becquerel (Bq)
What is meant by the activity of a radioactive source?
It is the number of decays per second.
What device can you use to measure the amount of radiation given out by a radioactive source in a certain direction?
Geiger counter.
What monitoring device do all people working with radiation have to wear?
Radiation badge
What is meant by the half-life of a radioactive source?
It is the time taken for the activity(or the number of radioactive particles present) to drop by half.
What is meant by the random nature of radioactive decay?
That radiation can not be predicted. You can not tell which atom will decay next or increase (or slow)down the rate at which radioactive sources decay.
Which type of radiation emitted does not change the type of atom the isotope is?
Gamma
How many half-lives would it take for the activity of a radioactive source to drop to 25% of its original level?
2 half-lives
Which type of radiation would be used for a medical tracer, such as checking kidney function? (PHYSICS ONLY)
Gamma
Which type of radiation would be used during radiotherapy to kill cancerous cells such as brain tunours? (PHYSICS ONLY)
Gamma
Why is radioactive iodine used to check the kidney function of a patient? (PHYSICS ONLY)
HL = 8 days, emits gamma radiation, decays into a stable product
What factors do you have to consider for when chossing a radiactive isotope as a medical tracer? (PHYSICS ONLY)
The half-life, and the type of radiation emitted by it.
Where does 50% of the background radiation come from? (PHYSICS ONLY)
air (radon gas that seeps from ground from radioactivity rocks)
Where does the background radiation around us come from? (PHYSICS ONLY)
radon gas, medical, ground, food and drink, cosmic rays,
Explain what is meant by nuclear fission? (PHYSICS ONLY)
The splitting of an atoms nucleus into two smaller nuclei, releasing energy and neutrons in the process.
What fuel is used in nuclear power stations? (PHYSICS ONLY)
Uranium and Plutonium
What is required to start the nuclear fission process in Power stations? (PHYSICS ONLY)
Absorbption of an neutron by the nucleus.
What percentange of U-235 is required for the fuel rod to be fissionable and undergo a successful chain reaction? (PHYSICS ONLY)
3%
What do the control rods do in a nuclear reactor? (PHYSICS ONLY)
The can be lowered to slow down the rate of reaction.
What is the role of the moderator in a nuclear reactor? (PHYSICS ONLY)
It slows down the fission neutrons released during fission so they can be absorbed by further nuclei.
What material is the nuclear reactor core made out of and why? (PHYSICS ONLY)
Steel to withstand the high temperatures and pressure
What is the metal nuclear reactor enclosed in and why? (PHYSICS ONLY)
Thick concrete walls to absorb any radiation which escapes through the reactor walls.
What is meant by nuclear fusion? (PHYSICS ONLY)
It is when two smaller nuclei join together to form a larger nuclei.
What is the majority of fusion taking place in stars? (PHYSICS ONLY)
Hydrogen fuses with Hydrogen to form Helium
Why is fusion a difficult process to manage outside of stars? (PHYSICS ONLY)
High temperatures are required, so the two nuclei are moving fast enough to overcome the repusive force due to both being positively charged.
In a nuclear fusion reactor, how is the plasma heated to get to the high temperatures required? (PHYSICS ONLY)
Using electric currents.
Why does radioactive waste need to be stored securely? (PHYSICS ONLY)
It remains radioactive so needs to be carefully stored to prevent contamination into the environment.
Why does radioactive waste need to be stored for many years? (PHYSICS ONLY)
It remains radioactive for a long time as it has a very long half life.
How is high level nuclear waste stored after decommisioning a nuclear power station? (PHYSICS ONLY)
Under ground in large water tanks to keep them cool.
What are the units which background radiation is measured in? (PHYSICS ONLY)
Sv (sieverts)
