Atomic History

Question 1

Dalton

Answer 1

All atoms of one element are the same, and are different from the atoms of another element. Atoms in his model were tiny and indivisible.

Question 2

Thompson

Answer 2

Discovered Electrons by cathode rays.
plum pudding model where negatively charged electrons move in a ‘sea’ of charge in a positively charged atom.

Question 3

Rutherford

Answer 3

Gold foil experiment. Fired alpha particles which passed through, showing most of the atom was empty space. Some alpha particles bounced back showing a densely packed positive nucleus with electrons orbiting the atom.

Question 4

Bohr

Answer 4

Electrons orbit the nucleus on paths. Planetary model provided an explanation for the difference in energy of electrons at different distances from the nucleus.

tiny positive nucleus orbited by negatively charged electrons. E orbited in shells of fixed size.