Radioactivity and particles

• What are the particles that make up an atom?

  Proton, neutron, electron
• What is the charge of a proton?

  Positively charged
• What is the charge of a neutron?

  Neutral, no charge
• What is the charge of an electron?

  Negatively charged
• Describe the structure of the atom.

  • Positively charged nucleus
  • Nucleus contains protons and neutrons
  • Negatively charged electrons orbit nucleus
  • Electrons orbit at different distances
• What is an isotope of an element?

  Atoms with same atomic number, different mass number
• What is the atomic number?

  Number of protons
• What is the mass number?

  Number of protons plus neutrons
• What is the relative mass of a proton?

  1 unit
• What is the relative mass of a neutron?

  1 unit
• What is the relative mass of an electron?

  Negligible mass
• What is the relative charge of a proton?

  +1
• Why is an atom neutral?

  • Same number of protons and electrons
  • Proton charge is +1, electron charge is -1
  • Charges balance, resulting in no overall charge
• How does an atom become a positive ion?

  By losing its outer electrons
• What types of radiation are emitted from unstable nuclei?

  • Alpha particles
  • Beta minus particles
  • Gamma rays
  • Neutron radiation
• Which types of radiation are ionising?

  Alpha, beta, gamma rays
• What is background radiation?

  Radiation that is always around
• Describe sources of background radiation.

  • Unstable nuclei in rocks (releases radon gas)
  • Radiation used in medicine
  • Released from food and water
  • Living things absorb radioactive material
  • Cosmic rays from the sun
• What equipment can detect radiation?

  Geiger-Müller detector, photographic film
• How do you measure and detect background radiation?

  • Geiger-Muller (GM) Detector: counts radiation pulses
  • Photographic film: darkens with radiation exposure
• Order the types of ionising radiation from least to most ionising.

  1. Gamma
  2. Beta
  3. Alpha
• Order the types of ionising radiation from most to least penetrating.

  1. Gamma
  2. Beta
  3. Alpha

  • Ionising power and penetration are inversely proportional
• What is an alpha particle?

  A helium nucleus (2 neutrons, 2 protons)
• What is a beta particle?

  An electron emitted from the nucleus
• What is a gamma ray?

  High energy electromagnetic wave
• What process involves a neutron splitting into a proton and an electron?

  Beta decay