Chapter 1 (Atomic Structure)

Question 1

Describe how J.J. Thompsons model was different from Daltons?

Answer 1

Dalton described atoms as solid spheres wheras J.J. decsribed them as a positively charged ‘pudding’ containing negatively charged particles (electrons) throughout.

Question 2

Explain how Rutherfords gold foil experiement provided eveidence that Thompson’s model was wrong?

Answer 2

If Thompsons plum pudding model was correct the alpha molecules fired at the sheet of gold should have been deflected by the positive pudding that made up the majority of the atom however most of the alpha particles passed straight through the gold atoms and only a small quantity were deflected.

Question 3

Describe Rutherfords model of the atom?

Answer 3

Rutherfords model consists of a tint positvely charged nucleus at the centre surrounded by a cloud of negative electrons, with most of the atom being empty space.

Question 4

Desribe the main features of Bohr’s model of the atom?

Answer 4

In Bohr’s model the electrons exist as fixed shells with each shell having a fixed energy. When an electron moves between shells an electromagnetic radition is emitted or absorbed.

Question 5

List the order of when each model of the atom was proposed?

Answer 5

Dalton - Solid spheres
J.J. Thompson - Plum pudding
Rutherford - Gold foil experiment lead to ‘cloud’ idea
Bohr - Idea of fixed sub shells

Question 6

What ideas about the atom did Gilbert Lewis present?

Answer 6

1. The inertness of the noble gasses was related to their the full outer shell.
2. Ions were formed by atoms losing or gaining electrons.
3. Atoms could bond by sharing electrons to form full outer shells.

Question 7

When and whom discovered elements?

Answer 7

Robert Boyle in 1661.