Chemistry - nuclear model

• What was the belief about atoms before their discovery?

  Atoms were thought to be tiny indivisible spheres
• What did the plum pudding model suggest about the structure of an atom?

  It suggested a ball of positive charge with embedded electrons
• Who proposed the plum pudding model?

  1. J. Thomson
• What did Rutherford's experiment with alpha particles reveal about the atom?

  Most alpha particles passed straight through the atom
• What did Rutherford conclude about the mass of an atom?

  The mass is concentrated at the center, the nucleus
• How did Niels Bohr adapt the nuclear model of the atom?

  He suggested electrons orbit the nucleus in fixed paths
• What particles did James Chadwick discover in the nucleus?

  Neutrons
• Compare the plum pudding model and the nuclear model of the atom.

  • Plum pudding model:
  • Positive charge throughout
  • Electrons embedded in the positive mass
  • No empty space
  • Nuclear model:
  • Positive charge concentrated in the nucleus
  • Electrons orbiting outside the nucleus
  • Most of the atom is empty space
• How long did it take for Dalton's ideas about atoms to be fully accepted?

  100 years
• What is the current understanding of the structure of an atom?

  Atoms consist of protons, neutrons, and electrons
• What does the symbol 'e-' represent in the current nuclear model?

  Electrons
• What does the symbol 'p' represent in the current nuclear model?

  Protons
• What does the symbol 'n' represent in the current nuclear model?

  Neutrons
• What was the significance of the discovery of the electron in atomic theory?

  It led to the development of the plum pudding model
• How did the understanding of atomic structure evolve from Dalton to modern atomic theory?

  From indivisible atoms to complex structures with subatomic particles