998362
| Pregunta | Respuesta |
| What is radioactive decay? | The spontaneous change in an unstable element, giving out radiation and often turning the atom into a new element. |
| What two types of particle are there in a nucleus and which of these decides what the element is? | There are protons and neutrons - an element always has the same amount of protons, though they can have different amounts of neutrons. |
| What three kinds of radiation are there? | alpha particles, beta particles, gamma radiation |
| What four stages are there to Rutherford's experiment? | Start with gold foil rolled out so thin it's just a few atoms thick, direct a source of alpha radiation at the gold in a vacuum chamber, watch for flashes of light as the particles strike the detecting screen, count where the flashes land to see how much of the alpha radiation is detected. Do this tens of thousands of times. |
| What did the data from the Rutherford experiment show? | That there must be a tiny, positive, heavy thing in the center of every atom. This is because the positive nucleus was causing alpha particle scattering. |
| 'Atoms of the same element have different mass numbers because they have different numbers of neutrons in their nucleus.' What is this called? | isotopes |
| What two things is the element produced by nuclear decay called? | The daughter product or the decay product. |
| Describe alpha radiation. (3 points) | A small, high speed particle with a positive charge. It's a helium nucleus in the sense that it has 2 protons and 2 neutrons and then becomes a helium atom by gaining electrons. It's most easily stopped but also the most ionising. |
| Describe beta radiation. (3 points) | Beta particles are smaller, higher-speed particles with a negative charge. Once they slow down they're actually just an electron that used to be a neutron. They travel further than alpha particles and are harder to stop, but also less ionising. |
| Describe gamma radiation. | High-energy electromagnetic radiation, that is very penetrating, has no mass and has a very week ionising effect. |
| What three uses does gamma radiation have? | It can sterilise medical instruments, sterilise hygiene products (such as tampons) and be used for the irradiation of herbs. |
| What is radiation dose and what is it measured in? | A measurement of the possible harm radiation could do to the body, in mSv. |
| Why are flight crews at risk from radiation? | They absorb lots of cosmic rays considering they fly so much. |
| What is contamination and what is the most dangerous form of it? | When a radiation source gets inside the body or on the clothes - alpha is the worst, as it's the most ionising and doesn't travel far. |
| What three precautions do many radiation workers, for example medical staff, often take when working with radiation? | Using protective clothing and screens, wearing gloves and aprons and wearing devices that monitor the radiation dose. |
| Why did lots of German silver miners die over 400 years ago? | They were breathing in radon gas which is radioactive and causes lung cancer. |
| What is the amount of radiation from a radioactive material called? | It's activity. |
| What is 'half-life'? | The time taken for the amount of a radioactive element in a sample to fall to half it's original value. |
| How does medical imaging work? | The patient takes a radioactive substance which is taken up by an organ which doesn't know it's radioactive. The gamma rays pass through the body and are picked up by a gamma camera, and show which parts of the organ are working and have therefore absorbed the radioactive substance. |
| How does radiotherapy work? | The patient has surgery to remove the tumor, takes a pill, the damaged tissues absorb some of the ingredients in the pill and the radioactive materiel gets absorbed too, which then emits (beta) radiation that kills the remaining cancerous cells. |
| In nuclear fission, what is the name and equation for the rule that explains why so much energy is released? | Einstein's equations states that energy = change in mass x speed of light squared |
| How does a nuclear power stations control the rate at which uranium decays? | It controls the chain reactions that occur in the fuel rods by raising or lowering control rods. |
| What three levels of nuclear waste are there and what these each mean? | Low-level waste is things like tools that have been contaminated by short lived waste, intermediate-level waste is short lived waste that humans do have to be protected from and high-level waste which is highly reactive and hot, used in making nuclear bombs. |
| Where is the biggest nuclear site in the UK and who is responsible for clearing up waste in this country? | Sellafield, and the Nuclear Decommissioning Agency. |
| What force holds protons and neutrons together? | The strong nuclear force. |
| How does nuclear fusion work? | Two different isotopes of hydrogen are repelled by the electrostatic force but if pushed hard enough together combine due to the strong nuclear force, which releases loads of energy. |
| What two advantages would there be of fusing hydrogen on earth, aside from the amount of energy it supplies? | The fuel involved would be water (abundant) and the nuclear waste produced would be minimal. |
| What do hydrogen ions form when heated enough and how is this kept away from the sides of a reactor? | They form a plasma, and don't touch the sides because they're kept away by magnetic plates. |
| What's the name of the huge project investigating fusion? | ITER (the way in Latin) |
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