History of Atomic Theory Chemistry Tutorial
- Around 400 B.C. Democritus, a Greek philosopher, proposed that matter was made up of small, hard, indivisible particles, which he called atoms.
Democritus offered no real evidence to support his idea, and it was not widely believed.
- The development of modern atomic theory begins in the late 1700's.
- A timeline for the major steps in the development of modern atomic theory is shown below:
|Contribution||"Atom" defined||"Plum pudding" model||"Nuclear" model||"Planetary" model|| neutron
| Quantum Mechanical model
(Pauli exclusion principle)