Atomic model - history and structure

Question 1

In 1897, JJ Thomson realised what about atoms?

Answer 1

That they were not solid spheres - they measuring charge and mass he reaslised that an atom also contained small negatively charged particles - electrons.

Question 2

What is the plum pudding model of the atom?

Answer 2

JJ Thomson’s image of the atom - positively charged soup with negatively charged electrons spread throughout the soup. Atoms did not have a solidity to them.

Question 3

What was the gold foil experiment?

Answer 3

Ernest Rutherford with Hans Geiger and Ernest Marsden fired positively charged alpha particles at a thin sheet of gold foil.
They expected that the particles would pass through the foil, but instead some were bounced back as if they had hit something solid. The plum pudding model couldn’t explain - there must be a solid centre bouncing the alpha particles back.

https://www.youtube.com/watch?v=p7O-CPFzwUQ

Question 4

What was Rutherford’s description of the atom?

Answer 4

The mass of the atom had to be concentrated in a positively charged nucleus; this was surrounded by negatively charged electrons. The rest of the atom was empty space.