Atomic Models

Question 1

What name was given to J J Thomson’s model of the atom?

Answer 1

The plum pudding model

Question 2

Name the scientists who conducted the gold foil experiment in 1909

Answer 2

Ernest Rutherford, Hans Geiger and Ernest Marsden

Question 3

Explain how the gold foil experiment provided evidence that Thomson’s model was wrong

Answer 3

If Thomson’s model was correct the alpha particles fired at the sheet of gold should have been deflected very slightly by the positive “pudding” that made up most of the atom. Instead, most of the alpha particles passed straight through the gold atoms, and a very small number was deflected backwards

Question 4

Describe Rutherford’s model of the atom

Answer 4

Rutherford’s model has a tiny positively charged nucleus at the centre surrounded by a “cloud” of negative electrons. Most of the atom is empty space

Question 5

Describe Bohr’s model of the atom

Answer 5

In Bohr’s model the electrons only exist in fixed shells and not anywhere in between. Each shell has a fixed energy. When an electron moves between shells electromagnetic radiation is emitted or absorbed. Because the energy of the shells is fixed, the radiation will have a fixed frequency.

Question 6

Describe how J J Thomson’s model of an atom was different from Daltons model

Answer 6

Dalton described atoms as solid spheres whereas JJ Thomson suggested that atoms were not solid spheres - he thought they contained small negatively charged particles in a positively charged “pudding”