radiation

Cards (32)

  • what are atoms made up of?

    - positively charged protons
    - neutral neutrons
    - negatively charged electrons
  • what orbits an atoms nucleus?

    electrons made up of protons and neutrons
  • how are atoms neutral?

    - they contain equal numbers of positive protons and negative electrons
    - they have no overall charge
  • ionisation
    the gain or loss of electrons from an atom
  • what does ionisation result in?

    atoms becoming ions (charged particles)
  • what happens if an atom gains a negative electron?

    it becomes a negative ion
  • what happens if an atom loses a negative electron?

    it becomes a positive ion
  • when does ionisation occur?
    ionisation can occur due to radioactive particles or waves, which are emitted from the nucleus of an unstable atom
  • radioactive decay
    a random process (it cannot be predicted)
  • alpha radiation
    - made up of two protons and two neutrons
    - has the same structure as the nucleus of a helium atom
    - have the greatest ionisation density of the three types of nuclear radiation
    - completely absorbed by a few centimetres of air or a single sheet of paper
    - least penetrative radiation
  • beta radiation
    - a fast-moving electron ejected from the nucleus of an atom
    - result in a neutron in the nucleus becoming a proton
    - weakly ionising
    - absorbed by a few millimetres of aluminium
  • gamma radiation
    - a gamma ray is a high-energy electromagnetic wave
    - travel through air at 3.0×10^8 ms-1, after being emitted from the nucleus of an atom
    - weakly ionising
    - mostly absorbed by several centimetres of lead
    - most penetrative radiation
  • background radiation sources
    - the ground
    - the air
    - building materials
    - food
    - cosmic rays from space
  • activity
    the number of nuclei in a radioactive substance which decay every second
  • half-life
    the time taken for the activity of a radioactive source to decrease by half
  • how to reduce the dose of nuclear radiation received
    - increase distance
    - decrease time
    - wear protective clothing
    - use shielding
  • applications of nuclear radiation
    - electricity generation (fission and fusion)
    - cancer treatment (radiotherapy)
    - other industrial uses (thickness detection of materials)
    - other medical uses (sterilisation of medical equipment, tracers)
    - other applications (smoke detectors)
  • absorbed dose
    - the energy absorbed per kilogram of tissue from radiation
    - measured in grays, Gy
  • equivalent dose, H
    the biological effect (harm) of radiation on living things depends on ~
    - the type of radiation (α, β or γ)
    - the type of tissue exposed to the radiation
    - the absorbed dose
    - measured in sieverts, Sv
  • equivalent dose rate, H (with a dot on top of the H)
    measured in Sv h-1 or Sv year-1 (or any other appropriate unit)
  • average annual background radiation in the UK
    2.2 mSv
  • annual effective dose limit for a member of the public
    1 mSv
  • annual effective dose limit for a radiation worker
    20 mSv
  • nuclear fission
    - the splitting of a large nucleus into smaller nuclei
    - this process releases energy
    - can be spontaneous, which means that it occurs at random at a time which cannot be predicted
  • chain reaction
    - occurs when the neutrons released from a fission reaction split subsequent nuclei and the process continues
    - responsible for the production of energy in a nuclear reactor
  • nuclear fusion
    - the joining of two smaller nuclei to form a larger nucleus
    - this process releases energy
    - the process by which stars produce heat
  • state one advantage of generating electrical energy by a nuclear fission power station
    - a large amount of energy is produced for a small amount of fuel
    - no pollution is given off
  • state conditions needed for nuclear fusion to occur
    - very high temperatures
    - a plasma confined by a magnetic field
  • state one advantage that generating electrical energy by a nuclear fusion would have
    - a large amount of energy is produced for a small amount of fuel
    - no pollution is given off
    - no radioactive waste is produced
  • what are benefits of developing nuclear fusion?
    - abundant fuel
    - less radioactive waste
    - safer
  • what are challenges of developing nuclear fusion?
    - high temperature requirements
    - containment issues
    - high cost of development
  • which type of radiation is suitable as a tracer in the human body?
    gamma radiation ~
    - least ionising
    - penetrates body tissues
    - detectable outside the body