Alpha Scattering experiment

• What did ancient Greeks believe about atoms?

  Atoms are tiny spheres that cannot be divided
• When was the discovery of electrons made?

  In 1897
• What did the discovery of electrons imply about atoms?

  Atoms have an internal structure
• What is the name of the model that replaced the idea of indivisible atoms?

  The Plum Pudding model
• How is the Plum Pudding model described?

  As a ball of positive charge with electrons embedded
• What experiment did scientists conduct to test the Plum Pudding model?

  The alpha scattering experiment
• Why is the alpha scattering experiment important?

  It changed the way we think about atoms
• What material did scientists use for the alpha scattering experiment?

  Gold foil
• Why did scientists use gold for the foil?

  It can be hammered into very thin foil
• What are the particles fired at the gold foil called?

  Alpha particles
• What charge do alpha particles have?

  Positive charge
• What did the scientists conclude from most alpha particles passing through the foil?

  Atoms are mainly empty space
• What did the deflection of some alpha particles indicate?

  The center of the atom has a positive charge
• What does the bouncing back of some alpha particles suggest?

  The center of the atom contains a great deal of mass
• What is the central part of an atom called?

  The nucleus
• What does the nuclear model state about the structure of an atom?

  Most of the atom is empty space with a nucleus
• What surrounds the nucleus in the nuclear model?

  Negative electrons
• What led to the replacement of the Plum Pudding model?

  • Results from the alpha scattering experiment:
  • Most alpha particles passed through, indicating empty space
  • Some were deflected, indicating a positive center
  • Some bounced back, indicating a massive center
• What are the key differences between the Plum Pudding model and the Nuclear model?

  Plum Pudding Model:

  • Positive charge with electrons embedded

  
  

  Nuclear Model:

  • Mostly empty space
  • Positive nucleus at the center
  • Electrons surrounding the nucleus