Development of the Model of the Atom

• What was thought about atoms before the discovery of the electron?

  Atoms were thought to be tiny spheres.
• What did the discovery of the electron lead to in atomic theory?

  It led to the plum pudding model of the atom.
• What does the plum pudding model suggest about the atom?

  The atom is a ball of positive charge.
• What are the components of the plum pudding model?

  Positive charge and embedded negative electrons.
• What did Rutherford's experiments conclude about atomic mass?

  Atomic mass is concentrated at the nucleus.
• What did Rutherford's findings indicate about the nucleus?

  The nucleus is positively charged.
• How did the nuclear model replace the plum pudding model?

  The nuclear model showed mass concentrated in the nucleus.
• Who adapted the nuclear model to include electron orbits?

  Niels Bohr adapted the nuclear model.
• What did Bohr suggest about electrons in the nuclear model?

  Electrons orbit the nucleus at specific distances.
• What did later experiments reveal about the positive charge of the nucleus?

  It could be subdivided into smaller particles.
• What name was given to the particles that make up the nucleus?

  Protons and neutrons make up the nucleus.
• What evidence did Chadwick provide regarding neutrons?

  He showed the existence of neutrons in the nucleus.
• How long after the nucleus became accepted was Chadwick's work?

  About 20 years later.
• What was the scientific community's reaction to the acceptance of the nucleus?

  It became an accepted scientific idea.
• What are the key models of atomic structure in historical context?

  • Plum Pudding Model: Positive charge with embedded electrons.
  • Nuclear Model: Mass concentrated in the nucleus.
  • Bohr Model: Electrons orbiting the nucleus at specific distances.