1.1.3 - Development of the Model of the Atom

Describe the plum-pudding model.

The atom is a ball of positive charge with negative electrons embedded in it.

Describe the alpha-scattering experiment.

• Aimed alpha particles at a thin gold foil.

• Most particles went straight through, some were slightly deflected, and a few bounced back.

  • This showed that atoms are mostly empty space with a small, dense, positively charged nucleus in the center.

What was discovered after the Rutherford model/alpha scattering experiment?

The mass of an atom was concentrated at the center (nucleus) and that the nucleus was charged.

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.

Describe the structure of an atom.

Has a small central nucleus (made up of protons and neutrons) around which there are electrons.