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SP6
GCSE Separate Science Physics
| Question | Answer |
|---|---|
| What does the particle theory/kinetic theory explain | Properties of solids, liquids and gases |
| " What are the three particles in the atom? | Proton, neutron and electron |
| Which has negative charge? | Electron |
| Describe the pum pudding model | Pudding made of positively charged material with negatively charged electrons |
| What did Rutherford fire at gold foil? | Alpha particals |
| What were the observationsfrom this experiment? | Most alpha travelled straight through,Some were slightly deflected,A few rebounded |
| What did he discover about the structure of the atom from these observations | Most of the atom is empty space,There is a tiny positive nucleus at the centre,The nucleus is very dense. |
| What is the radius of the nucleus? | 1 x 10-15 m |
| What is the radius of the atom? | 1 x 10-10 m |
| Where is the mass of an atom concentrated? | The nucleus |
| What is the nucleus made of ? | Nucleons |
| What types of particle can nucleons be? | Protons and neutons |
| What is the relative mass of a proton and a neutron? | 1 |
| What is the relative mass of an electron? | 1/1835 |
| What is the proton number or atomic number? | The number of protons in the nucleus |
| What is the mass number of nucleon number? | Total number of protons and neutrons in the nucleus. |
| What are isotopes of an element? | Isotope of an element will have the same atomic number but different mass numbers as they contain different numbers of neutrons. |
| Name the 3 isotopes of carbon? | Carbon 12, carbon 13 and carbon 14. |
| 17 O 8 How many protons, neutrons and electrons does it contain | 8 protons, 9 neutrons, 8 electrons |
| What is background radiation ? | Exposure to low level radiation from space and natural radioactive substances in the environment. |
| What is the main source of background radiation in the UK? | Radon gas produced by rocks that contain small amounts of uranium. |
| Why is radon dangerous? | It can diffuse into the air from rocks and soil and build up on poorly ventilated houses. |
| What hospital treatments can contribute to a person’s back ground radiation exposure? | X rays, Gamma ray scans, cancer treatment |
| What are cosmic rays ? | High energy charged particles streaming out from the sun. |
| What reduces cosmic rays? | Many are stopped by the upper atmosphere. |
| How can amount of radiation a person is exposed to be measured with a dosimeter? | The dose can be measured using photographic film which gets darker and darker with more exposure. |
| How does a Geiger Muller tube work? | Radiation passing through the tube ionises the gas inside it and produces a short pulse of current. |
| What is the count rate of a GM tube connected to a counter? | The number of clicks per second or minute |
| When an unstable nuclei decays and the nuclei becomes a new element, what changes? | The atomic or proton number |
| What happens to the atomic mass and atomic number during alpha decay? | The atomic mass decreases by 4 and the atomic number by 2 |
| What happens to the atomic mass and the atomic number during beta(-) decay? | The atomic mass does not change and the atomic number increases by one |
| What happens to the atomic mass and the atomic number during beta(+) decay? | The atomic mass does not change and the atomic number decreases by one |
| Why do nuclei emit a gamma ray? | This is when the subatomic particles in the nucleus rearrange and the nucleus loses energy. This makes them more stable |
| What must be balanced in a nuclear equation? | The total mass number must be the same on each side and the total charges must be the same ( sum of the atomic numbers) |
| What is the new atomic mass if polonium -208 (208 84 Po) undergoes an alpha decay? | 204 |
| What is the new atomic number if Technetium (9943Tc) undergoes a beta (-) decay? | 44 |
| What happens in the nucleus during beta (-) decay? | A neutron changes into proton and ejects and electron from the atom |
| What happens to an unstable nuclei after it has decayed? | More stable |
| Define the activity of a source. | Number of nuclear decays per second |
| What units is activity measured in ? | Bequerels |
| Define half life | Time taken for half the unstable atoms to decay. Time taken for the original activity to halve |
| If an unstable isotope has a long half life does it take a long or short time to decay fully? | Long |
| Caesium – 137 has a half life of 30 years. If the original activity was 100Bq, what will the activity after 60years? | 100/2= 50, 50/2 =25Bq |
| Caesium – 137 has a half life of 30 years. If there were 100g originally what will be the mass of caesium atoms after 60years? | 60/30= 2 half lives so ¼ of original = 25g |
| Radon has a half life of 4 days, what fraction of radon will be left after 12 days? | 12/4= 3 half lives = 1/8 (1/2 x1/2x1/2) will be left |
| A sample containing Carbon 14 has an activity of 2Bq. How long ago did if have an activity of 8Bq? | Half life of carbon =6000 years (1)Number of half lives =3, so 18000 years |
| What effect do microorganisms have on food? | Cause them to decompose. |
| Why is food irradiated using gamma rays? | Kills microorganisms, making it safer to eat and it can be stored longer |
| What types of surgical instruments cannot be sterilised using heat? | Plastic instruments e.g. syringes |
| So how can plastic syringes be sterilised? | Placed in plastic bags and irradiated with gamma rays to kill microorganisms |
| Explain how a radioactive tracer can be used to detect leaks in underground water pipes? | A gamma traces is added to the water. A Geiger muller tube is placed on the surface. When a higher level of radiation is detected the leak must be underneath. |
| What source of radiation is used to check that paper is rolled to the same thickness? | Beta(-) |
| If the paper is too thick what happens in the machine? | The count rate decreases and so a computer then causes the pressure on the paper to increase. |
| What source of radioactivity is used in smoke alarms? | Alpha |
| What do the alpha particles do to the air in the smoke detector and how does this cause a current to flow? | alpha particles ionise the air, the ions are attracted to the electrodes producing a current.The |
| What happens when smoke enters the smoke detector? | Smoke gets in the gap, this slows down the ions, the current decreases and the alarm sounds. |
| When DNA is damaged through exposure to ionising radiation, what does this process produce? | A gene mutations |
| What is DNA | It contains the structures that control the cell |
| Which cells in the body if damaged could cause mutations in the next generation? | Sperm/egg/ gamete |
| Give three ways of reducing the intensity of ionising radiation you receive from handling a radioactive source | Use long tongs/ Stand a long distance, Don’t point source towards anyone, Shield with thick lead |
| How do medical staff lower their risk to exposure when working with radioactive sources? Give 2 methods | Reducing the time of exposure, Increasing their distance to the source, Shielding the source |
| Why are radioactive sources used to diagnose or treat medical conditions? | They are only used when the benefits outweigh the risks |
| What does the word irradiated mean? | Exposure to ionising radiation |
| What does the word contaminated mean for example a person becomes contaminated after a nuclear accident | Person gets particles of radiative material on skin/ inside body |
| What precautions should people take when cleaning up after a nuclear accident? Give 2 examples | Wear protective overalls., Wear masks, Limit the time of cleaning up for each person |
| Why are tracers put into the human body? | To diagnose medical conditions |
| How are tracers put into the body? | Injected into the bloodstream, swallowed, inhaled or injected into an organ. |
| What locates the tracer? | A gamma camera |
| What organ absorbs Iodine 123? | The thyroid gland |
| How would kypton 81m be used as a tracer? | It can be inhaled to investigate lung function |
| What does PET stand for? | Positron Emission Tomography |
| What happens when a positron tracer emits a positron in the body? | The positron meets an electron and they are both destroyed and produce 2 gamma rays in opposite directions. |
| Why do medical tracers have a short half life? | So that other parts of the body are affected as little as possible. |
| Where are radioactive tracers made? | Very close to the hospital as they decay quickly as they have a short half life. |
| What type of radiotheraphy is used externally? | Gamma rays. X rays or protons. |
| Describe nuclear fission | large nuclei split into smaller nuclei and release energy |
| Describe nuclear fusion | two small nuclei join together to form a larger nuclei |
| Name a nuclear fuel. | Uranium, plutonium |
| Are nuclear fuels renewable or non-renewable? | Non-renewable |
| Do nuclear power stations produce carbon dioxide? | No |
| What is the problem with nuclear waste?( | It is radioactive for millions of years, It is expensive to store |
| What does decommissioning mean? | Dismantling a power station at the end of its life. |
| Which industry has the highest death rate per unit of electricity produced? | Coal mining |
| Name a major nuclear accident. | Chernobyl, Fukishima |
| What happens when uranium absorbs a neutron? | It splits into 2 radioactive daughter nuclei plus 2 or more neutrons. |
| How is energy released in the fission reaction? | The daughter nuclei and neutrons have a high store of kinetic energy as they are moved at high speeds. |
| What is the energy of the products of fission transferred into? | Thermal energy |
| What is an uncontrolled chain reaction? | When the neutrons from each fission reaction are allowed to fission more uranium nuclei producing more neutrons |
| Where do uncontrolled chain reactions occur? | In nuclear bombs. |
| How is the chain reaction controlled in a nuclear reactor? | Control rods contain elements that absorb neutrons, they are placed between the fuel rods and can be moved up and down to control the fission rate. |
| Where is the uranium placed in a nuclear reactor? | In fuel rods in the core |
| What is the purpose of the moderator in the nuclear reactor? | To slow down neutrons, so they are more likely to cause fission |
| If the temperature of the reactor is becoming too hot what safety mechanism is there? | The control rods can be lowered into the core to slow the reaction down. |
| Name the part of a nuclear power station in the correct order to produce electricity? | Reactor core, heat exchanger, turbine, generator. |
| Name the three types of radiation and list: what they are made of, how penetrating they are, their charge and their ionizing ability | Radiation Made of Stopped by Charge /Ionising ability Range Alpha 2 protons 2 neutrons Paper +2 HighFew cms BetaElectron Few cm of aluminum-1 MediumFew ms GammaWave Few cms of Lead0 Low Few kms |
| Describe a use of radiation in the home | Alpha radiation is used in a smoke alarm. Smoke blocks alpha particles getting to a detector so sets off an alarm |
| Describe uses of radiation in medicine | Gamma rays are used to destroy tumors (radiotherapy) they can be used to sterilize medical equipment |
| What is background radiation? | Radiation that is present even in the absence of artificial sources of radiation |
| What are the main sources of background radiation? | Cosmic Rays from space Radon a radioactive gas released from granite Leaks from power stations |
| What do you use to detect radiation? | A Geiger Muller Counter |
| What are the risks of exposure to radiation? | Radiation may ionize DNA leading to mutations and cancer |
| What does fission mean? | Splitting an atom into smaller nuclei |
| What are isotopes? | Elements that have the same number of protons but different numbers of protons |
| How many protons, electrons and neutrons does this isotope have: | 6 protons Neutrons=12-6=6 neutrons ,6 electrons |
| Describe what happens in nuclear fission | A neutron is fired at uranium. The nucleus splits into two smaller nuclei called daughter nuclei- these are Barium and Krypton. This releases energy and 3 neutrons. The neutrons cause other fissions called a chain reaction |
| Describe the main steps in a nuclear power station | The nuclear reaction releases heat which boils water into steam. The steam turns a turbine connected to a generator which generates electricity. The electricity goes out into the national grid |
| What is nuclear fusion? Where does it occur | Joining nuclei together to release energy. It occurs in the stars. |
| What conditions are needed for fusion? | High temperature, High pressure and High density |
| Define atom | The smallest part of an element that can exist. |
| All substances are made up of…? | atoms |
| The radius of an atom is …? | 0.1 nm (1 x 1010 m) |
| The overall charge on an atom is… | zero/neutral |
| Define element | Contains only one type of atom |
| Substances found in the periodic table are…? | elements |
| Approximately how many elements are there? | 100 |
| Define isotope | An atom of the same element with different numbers of neutrons |
| Define radioactive decay | An unstable nucleus changes to become more stabe and gives out radiation |
| We cannot predict when a given atom will decay, this means that radioactive deacy is ….? | random |
| Define activity | Rate at which decay occurs |
| What are the units of activity? | Becquerels (Bq) |
| Define count rate | Number of decays recorded each second by a Geiger-Muller tube |
| Defne half life | The time taken for number of radioactive nuclei in a sample to halve OR time taken for count rate (or activity) from a sample to fall to half its initial value |
| Define contamination | The unwanted presence of materials containing radioactive atoms |
| Define irradiation | When an object is exposed to radiation |
| Does an irradiatied object become radioactive itself? | no |
| The process of radiation removing electrons from atoms to form ions is called…? | ionisation |
| If ionisation happens in DNA it can cause ___________ which may result in ____________ | mutations, cancer |
| Define peer review | Checking of scientific results by other scientific experts |
| Define mass number | The total number of protons and neutrons in an atom |
| Define atomic number | The number of protons in an atom (number of electrons is the same in a neutral atom) |
| Electrons in atoms are located in ___________ | energy levels |
| Absorption of radiation by an atom may result in ____________ moving to a ________________ energy level | electrons, higher |
| Emission of radiation from an atom may lead to _____________ moving to a ______________ energy level | electrons, lower |
| Who came up with the Plumb Pudding model of the atom | J J Thompson |
| Describe the Plumb Pudding model of the atom | A ball of positive charge with negative electrons embedded in it |
| Was the Plumb Pudding model correct? | no |
| What experiment did Rutherford do? | Alpha particle scattering |
| What did Rutherford's experiment reveal? | Atoms have a central area of positive charge with electrons surrounding it |
| Who discovered that electrons are located in energy levels? | Niels Bohr |
| What did Jame Chadwick discover about the atom? | That the nucleus contains neutrons as well as protons |
| What did John Dalton contribute to our understanding of atomic theory? | Matter is made up of descrete, spherical particles, known as atoms |
| Name the three subatomic particles | proton, neutron, electron |
| Which particles are located in the atoms nucleus | protons, neutrons |
| What is the charge of each subatomic particle? | proton +1, neutron 0, electron -1 |
| What is the mass of each subatomic particle? | proton 1, neutron 1, elecrton ≈ 0 |
| Name the three types of radiation | alpha, beta and gamma |
| What is an alpha particle? | two protons and two neutrons |
| What is a beta particle? | an electron |
| What is gamma radiation? | electromagnetic wave (NOT a particle) |
| What is the range of alpha radiation in air? | short - 5 cm in air |
| What is the range of gamma radiation in air? | unlimited in air |
| What's the range of beta radiation in air? | medium - about 1 m |
| What will absorb (stop) alpha radiation? | paper/skin |
| What will absorb (stop) beta radiation? | about 5 mm aluminium |
| What will absorb (stop) gamma radiation? | several centimetres of lead |
| What is the ionising power of alpha radiation? | very high |
| What is the ionising power of beta radiation? | medium |
| What is the ionising power of gamma radiation? | low |
| What is meant by the ionising power of radiation? | how likely it is to ionise atoms which it comes into contact with |
| How does alpha decay alter the mass number of the parent nucleus? | decreases by 4 |
| How does alpha decay alter the atomic number of the parent nucleus? | decreases by 2 |
| How does beta decay alter the mass number of the parent nucleus? | stays the same |
| How does beta decay alter the atomic number of the parent nucleus? | increases by 1 |
| How does gamma radiation alter the mass and atomic number of the parent nucleus | unchanged (energy is released as the particles in the nucleus reorganise to a lower energy arrangement) |
Created by:
Davenant Foundation School
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