Models of the Atom

Who proposed the following model for the atom?

"Atoms are solid spheres. Each element is made of a different type of atom."

• Bohr

• Chadwick

• Dalton

• Rutherford

In 1897, J J Thomson discovered the electron. This led him to propose the ____-pudding model of the atom.

The plum pudding model showed the atom as a ball of ________ charge with electrons stuck inside it.

What was the overall charge of an atom in the plum pudding model?

• Positive

• Negative

• Neutral

• It depends on the atom

In 1909, Ernest Rutherford performed his alpha scattering experiment. He fired alpha particles at very thin foil made of ____.

What was the expected result of the alpha scattering experiment if the plum pudding model was correct?

• Most of the alpha particles would pass straight through the foil.

• Most of the alpha particles would be completely reflected.

• The alpha particles would be absorbed by the gold foil.

• The gold foil would produce extra alpha particles.

Most of the alpha particles passed straight through the gold foil. This led Rutherford to propose that...

• most of the atom was empty space.

• there was a positively charged nucleus at the centre of the atom.

• the alpha particles were not aimed properly at the foil.

• the plum pudding model was correct.

Some of the alpha particles were reflected backwards by large angles. This led Rutherford to propose that...

• most of the atom was empty space.

• there was a positively charged nucleus at the centre of the atom.

• the alpha particles were not aimed properly at the foil.

• the plum pudding model was correct.

Which of these was a problem with Rutherford's atomic model?

• The negative electrons would be attracted to the positive nucleus and the atom would collapse.

• The negative electrons would be repelled by the positive nucleus and would fly off into space.

• The model left the atom with a positive charge.

• The model left the atom with a negative charge.

In Bohr's model, the electrons orbit the nucleus in ______.