Hazards and uses of radioactivity

• What is meant by the ‘half-life’ of a radioactive isotope?

  Time taken for the amount of atoms to halve
• Which two types of radiation will pass through a sheet of card?

  Beta and gamma
• Which two types of radiation would be deflected by an electric field?

  Alpha and beta
• Which type of radiation has the greatest range in air?

  Gamma
• Although there are some risks associated with nuclear power stations, it is likely that new ones will be built.  Give two reasons to justify the use of

  nuclear power

  Produces no pollutants

  produces a lot of energy for a small mass
• What is meant by the 'half-life' of a radioactive isotope?

  Time taken for the amount of atoms to halve
• Which two types of radiation will pass through a sheet of card?

  Beta and gamma
• Which two types of radiation would be deflected by an electric field?

  Alpha and beta
• Which type of radiation has the greatest range in air?

  Gamma
• Although there are some risks associated with nuclear power stations, it is likely that new ones will be built.

  Give two reasons to justify the use of nuclear power

  Produces no pollutants

  produces a lot of energy for a small mass
• What is the force which pulls the dust and gas together?

  Gravitational
• What do smaller masses attracted by a star become?

  Planets
• Why is the Sun stable?

  the gravitational forces and the radiation pressure are equal
• Describe what happens to the nucleus of an atom during nuclear fission

  It splits into smaller parts and neutrons are emitted
• Nuclear fusion


  the nuclei of two atoms joining together
• Electric current


  an electric charge moving through a metal
• Ionisation


  an atom losing an electron
• Nuclear fission


  the nucleus of an atom splitting into several pieces
• Explain briefly how stars like the Sun are thought to have been formed.

  -Dust and gas pulled together by gravity

  -nuclear fusion starts
• Stars are stable during the 'main sequence' period of the life cycle. Why?


  Forces are balanced
• What is released during both nuclear fission and nuclear fusion?

  Energy
• Explain briefly the difference between nuclear fission and nuclear fusion

  -fission is the splitting of a nucleus

  -fusion is the joining of nuclei
• Where does nuclear fusion happen naturally?

  Star
• Describe the process of nuclear fusion.

  Two nuclei join forming a larger nuclei
• Shortly after the 'big bang', hydrogen was the only element in the Universe. Explain how the other elements came to be formed.

  By fusion of hydrogen to helium and elements heavier than iron are only produced in a supernova
• Describe what happens to a star much bigger than the Sun, once the star reaches the end of the 'main sequence' period of its life cycle.

  star runs out of hydrogen and expands and cools forming a red super giant which explodes as a supernova becoming a neutron star
• What happens to the elements produced in a supernova?

  distributed throughout the Universe
• Explain the difference between a protostar and a main sequence star.

  a protostar is at a lower temperature as fusion hasn't started
• Describe how 'carbon capture' would prevent the build-up of carbon dioxide in the atmosphere.

  carbon dioxide is not released but is stored
• Explain the advantages of using energy from nuclear fuels to generate electricity rather than using energy from the wind.

  Concentrated source of energy that's able to generate continuously the energy from fission is used to heat water to steam to turn a turbine linked to a generator
• Explain how atoms of very heavy elements, such as gold (Au), were formed.

  Fusion of other elements during a supernova