ATOMIC STRUCTURE & RADIATION

• What is the definition of an atom?

  Same number of protons and electrons
• What defines an ion?

  Unequal number of electrons to protons
• What does mass number represent?

  Number of protons and neutrons
• What is the atomic number?

  Number of protons
• What occurs during radioactive decay?

  Unstable atoms emit radiation to become stable
• What device is used for detecting radiation?

  Geiger Muller tube
• What is the unit of measurement for radioactivity?

  Becquerel
• What does ionisation refer to in radiation?

  All radiation ionises
• What is the unit measuring the dose of radiation?

  Sievert
• What is the background level of radiation?

  Constant 18w level environment radiation
• What is half-life in radioactive decay?

  Time taken to reduce to half initial radioactivity
• What is contamination in the context of radiation?

  Unwanted presence of radioactive atoms
• What does irradiation mean?

  Person is exposed to radioactive source
• What is an isotope?

  Different forms of an element with same protons
• Who proposed that everything is made of small particles?

  Democritus
• What did John Dalton introduce in 1904?

  Solid spheres of different types
• Who discovered electrons in 1897?

  JJ Thompson
• What did Rutherford discover in 1911?

  Nucleus smaller than atoms
• What did Bohr discover in 1913?

  Shell of electrons
• Who discovered neutrons in 1932?

  Chadwick
• What are the properties of subatomic particles?

  • Neutron: Charge = none, Size = 1, Found in nucleus
  • Proton: Charge = +1, Size = 1, Found in nucleus
  • Electron: Charge = -1, Size = tiny, Orbits nucleus
• What are the characteristics of different types of radiation?

  • Alpha: Range in air = few cm, Ionising power = very strong, Stopped by paper
  • Beta: Range in air = few cm, Ionising power = medium, Stopped by aluminium
  • Gamma: Range in air = great distances, Ionising power = weak, Stopped by lead
• What are the changes in mass and atomic numbers during decay?

  • Alpha: Mass number -4, Atomic number -2
  • Beta: Mass number 0, Atomic number +1
  • Gamma: Mass number 0, Atomic number 0
  • Neutron: Mass number -1, Atomic number 0
• What are the uses of radioactive emissions?

  • Different isotopes have different half-lives
  • Tracers used within the body
  • Radiation therapy for treating illnesses
• What are the components of a nuclear reactor?

  • Fuel rods: Made of U-238, enriched with U-235 (3%)
  • Control rods: Made of boron, controls reaction rate
  • Concrete: Thick shield protects workers from neutrons
• What is nuclear fission?

  One large unstable nucleus splits into two smaller nuclei
• What is nuclear fusion?

  Two smaller nuclei join to make one larger nucleus
• Why is nuclear fusion difficult on Earth?

  Requires huge pressure and temperature
• Where does nuclear fusion occur naturally?

  In stars