Rutherford Scattering

• Who discovered evidence for the structure of the atom?

  Ernest Rutherford
• What method did Rutherford use to study the atom's structure?

  Alpha particle scattering
• What was the purpose of passing alpha particles through gold foil?

  To investigate angles of deflection

  
• What were the two main observations in the Rutherford Scattering Experiment?

  Angles of deflection and number of particles
• What apparatus was used in the Rutherford Scattering Experiment?

  • Source of alpha particles in lead container
  • Thin sheet of gold foil
  • Movable detector
  • Evacuated chamber

  
• Why was a lead container used in the experiment?

  To produce a collimated beam of alpha particles
• Why was the gold foil extremely thin?

  To prevent stopping alpha particles completely
• What property of gold made it suitable for the experiment?

  Its malleability
• Why was the apparatus placed in an evacuated chamber?

  To prevent alpha particles from colliding with air molecules
• What is an alpha particle?

  The nucleus of a helium atom
• What did the majority of alpha particles do when fired at gold foil?

  Passed straight through the foil

  
• What does the deflection of some alpha particles suggest?

  There is a positive nucleus at the center

  
• What does the small number of alpha particles deflected straight back indicate?

  The nucleus is extremely small and dense

  
• What is the conclusion drawn from Rutherford's experiment?

  • Atoms consist of small, dense positively charged nuclei
  • Surrounded by negatively charged electrons

  
• How much larger is an atom compared to its nucleus?

  About 100,000 times larger
• In the α-particle scattering experiment, what was measured at various angles?

  The number of α-particles incident per unit time
• What does the graph of n versus θ from 0 to 90° represent?

  The variation of α-particles with angle

  
• Why is the largest value of n at small angles?

  Most α-particles go straight through
• How does n change with increasing angle of deflection θ?

  n drops quickly with increasing θ
• What are the key observations from Rutherford's experiment?

  • Majority of α-particles passed through
  • Some α-particles deflected at small angles
  • Few α-particles deflected straight back