NS- Atomic Theory Timeline

Question 1

442 BC

Answer 1

Democritus, a Greek philosopher, proposed the idea that meter is made of tiny, indivisible,indestructible particles that he called atomos. He did this along with his teacher Leucippus. He didn’t have the necessary equipment to test his idea and therefore his ideas were eventually rejected.
Democritus’s Atom.

Question 2

1803

Answer 2

J.J Thomson, an English scientist was experimenting with gas discharge tubes when he noticed a movement in the tube. He called the movement cathode rays. The Rays moved from the negative end of the tube to the positive end. When he held a negative metal plate near the cathode ray, the Ray deflected away. The Rays were made of negatively charged particles (electrons).
Plum Pudding

Question 3

1909

Answer 3

Ernst Rutherford, the father of nuclear physics, developed a theory for the structure of an atom. He used the gold foil experiment. He used a thin sheet of gold foil and special equipment to shoot alpha particles (positively charged) at the gold foil. Most particles passed straight through the foil like it wasn’t there, some went straight back or were deflected as if they’d hit something. Atoms are made of a small positive nucleus. The positive nucleus reply the positive alpha particles. Atoms are mostly empty space.
Nuclear Atomic Model.