1.1.6 History of the Atom

• Describe the plum-pudding model.

  The atom is a ball of positive charge with negative electron embedded in it.
• Describe the Bohr/nuclear model and how it came about.

  The nuclear model suggests that electrons orbit the nucleus at specific distances (shells) - it came about from the alpha scattering experiments.
• Later experiments led to the discovery of smaller, positive particles in the nucleus; what are these particles called?

  Protons.
• What did the work of James Chadwick provide evidence for?

  The existence of neutrons in the nucleus.
• Mendeleev overcame some problems with the table by doing what? He also changed the order of some elements based on what?

  Leaving gaps; atomic weights.