Atomic Structure

• what is alpha stopped by?

  paper
• What is nuclear fission?

  The splitting of a large atomic nucleus into smaller nuclei
• What is the issue with fusing nuclei

  Nuclei is positive, so as 2 nuclei approach each other, they will repel because they have the same charge
• What is nuclear fusion?

  When 2 small, light nuclei join together to make 1 heavy nucleus
• What is the unit to measure radiation dose?

  sievert
• State two precautions people working with nuclear radiation should take to reduce the risk to their health?

  • Protective clothing
  • limit time of exposure
• What is the strength of gamma radiation ionisation?

  Weak
• What is the strength of beta radiation ionisation?

  Quite
• What is the strength of Alpha radiation ionisation?

  Strong
• What are contamination disadvantages?  

  • Radioactive isotopes may not go where they are wanted
  • exposure can lead to damage to healthy cells
  • radioactive isotopes may still be left behind
• What is the half-life of a radioactive isotope?

  • Time it takes for the number of nuclei of the isotope in a sample to halve
  • time it takes for the activity from a sample containing the isotope to fall to half its initial level
• What describes the process of radioactive decay?

  Random
• The number of the decays per second recorded by detector is known as what

  Count rate
• What is 1 Bq?

  1 decay per second
• With alpha decay the atomic number goes down by what and the mass number goes down by what?

  2 and 4
• With beta decay the mass number does what and the atomic number goes up by what?

  Stays the same and 1
• How far do gamma particles travel?

  Virtually unlimited range
• What is gamma stopped by

  • a few cm thick lead sheet
  • 1 cm thick concrete
• What is beta stopped by?

  Aluminium
• What are the differences between the plum pudding model and the nuclear model of the atom?

  • The nuclear models mass is concentrated at the centre whereas plum pudding model mass is evenly distributed
  • nuclear model positive charge occupies only small part of the atom, plum pudding model positive charge spread throughout the atom
  • nuclear model electrons orbits some distance from the nucleus plum pudding electrons are embedded in the mass of positive charge
  • nuclear model the atom is mainly empty space and whereas in the pump pudding model it is mainly a solid mass
• What is the process of nuclear fission?

  1.  In a nuclear reactor a neutron is absorbed into a nucleus
  2. causes the nucleus to become uranium 236 which is violently unstable
  3. Nucleus splits into 2 large fragments called daughter nuclei
  4. 2 or 3 neutrons explode out fission reactor
  5. neutrons can collide with other uranium nuclei to cause further fission reactions
• What are contamination advantages

  • Imaging processes can replace some invasive surgical procedures
  • radioactive isotopes can be used as medical pacers
  • use of isotopes with a short half-Life means exposure can be limited
• What are irradiation disadvantages?

  •  can be harmful
  • cause mutations
  • may not kill all bacteria
• What are irradiation advantages

  sterilisation can be done without high temperatures 
• What is irradiation?

  Exposing an object to nuclear radiation
• How far do beta particles travel?

  1m
• How far do alpha particles travel?

  A few cm
• What is radioactive decay?

  When an unstable nucleus gives out radiation
• What equipment measures the activity of a radioactive source?

  Geiger Muller tube
• What is an isotope of an element?

  Atoms of the same element can have different number of neutrons
• What is the equation to find the neutron number

  Neutron number = mass number - atomic number
• The mass number is the total number of what in an atom?

  Protons and neutrons
• What is the number of protons in an atom called?

  The atomic number
• What is the charge, relative mass, and location in the atom of an electron?

  • -1
  • almost zero
  • shells
• What is the charge, reactive mass, and location in the atom of a neutron?

  • Neutral
  • 1
  • nucleus
• What is the charge, relative mass, and location in the atom of a proton?

  • Positive
  • 1
  • nucleus
• What is radioactive contamination?

  When unwanted presence of radioactive isotopes are on materials
• True or false? The irradiated object does not become radioactive itself

  True