Atomic Structure

• What can a gas do when pressure changes?

  It can be compressed or expanded
• What does pressure produce in a gas container?

  A net force at right angles to the wall
• How does increasing the volume of a gas affect its pressure at constant temperature?

  It leads to a decrease in pressure
• What is the equation relating pressure and volume for a fixed mass of gas at constant temperature?

  Pressure × Volume = constant
• What are the units for pressure and volume in the gas equation?

  Pressure in pascals, volume in m³
• How can you calculate the change in pressure or volume of a gas?

  By using the gas equation
• What happens to the internal energy of a gas when work is done on it?

  It increases the internal energy
• How does doing work on a gas affect its temperature?

  It can cause an increase in temperature
• What is ionising radiation?

  Radiation that can remove electrons from atoms
• Why was the discovery of radioactivity significant?

  It led to understanding atomic structure
• What is the radius of an atom approximately?

  About $1 \times 10^{-10} \text{ metres}$
• What composes the nucleus of an atom?

  Protons and neutrons
• Where is most of the mass of an atom concentrated?

  In the nucleus
• How do electrons arrange themselves in an atom?

  At different distances from the nucleus
• What happens to electron arrangements with electromagnetic radiation absorption?

  Electrons move to higher energy levels
• What is the atomic number of an element?

  The number of protons in the nucleus
• What is the mass number of an atom?

  The total number of protons and neutrons
• What are isotopes?

  Atoms of the same element with different neutrons
• What happens to atoms when they lose outer electrons?

  They turn into positive ions
• What did the discovery of the electron change about atomic theory?

  It led to the plum pudding model
• What did the alpha particle scattering experiment reveal?

  Mass is concentrated in the nucleus
• How did Niels Bohr modify the atomic model?

  He suggested electrons orbit the nucleus
• What did James Chadwick discover?

  The existence of neutrons in the nucleus
• What is radioactive decay?

  A random process of nucleus changing
• How is activity measured?

  In becquerel (Bq)
• What is a beta particle?

  A high-speed electron from the nucleus
• What does alpha decay do to the nucleus?

  It decreases both mass and charge
• What does beta decay do to the nucleus?

  It increases the charge but not mass
• What is the half-life of a radioactive isotope?

  The time for nuclei to halve
• What is radioactive contamination?

  Unwanted presence of radioactive materials
• What is irradiation?

  Exposing an object to nuclear radiation
• What is background radiation?

  Radiation from natural and man-made sources
• How is radiation dose measured?

  In sieverts (Sv)
• Why do hazards differ with radioactive isotopes?

  Due to their different half-lives
• How is nuclear radiation used in medicine?

  For exploration and destruction of tissue
• What are the properties of alpha particles, beta particles, and gamma rays?

  • Alpha particles:
  • Consist of 2 protons and 2 neutrons
  • Low penetration, high ionising power
  • Beta particles:
  • High-speed electrons
  • Moderate penetration, moderate ionising power
  • Gamma rays:
  • Electromagnetic radiation
  • High penetration, low ionising power
• Compare the hazards of radioactive contamination and irradiation.

  • Radioactive contamination:
  • Unwanted radioactive materials present
  • Hazard due to decay of contaminating atoms
  • Irradiation:
  • Exposure to nuclear radiation
  • Object does not become radioactive
• What are the uses of nuclear radiation in medicine?

  • Exploration of internal organs
  • Control or destruction of unwanted tissue
• What are the key concepts related to half-lives in radioactive decay?

  • Half-life: Time for nuclei to halve
  • Related to random nature of decay
  • Varies widely among isotopes
• What is the significance of peer review in radiation studies?

  • Ensures findings are checked
  • Promotes scientific accuracy and reliability