The document summarizes the historical development of atomic theory from ancient Greece to the early 20th century. It describes the early ideas of Democritus and Aristotle, followed by John Dalton's atomic theory in the early 1800s which proposed that all matter is made up of atoms. It then discusses J.J. Thomson's discoveries of the electron using Crookes tubes and his "plum pudding" model of the atom. Finally, it outlines Ernest Rutherford's refinement of the atomic model through his gold foil experiment and discovery of the nucleus, and the later quantum mechanical model including the discovery of the neutron by James Chadwick.

1. Historical Development of Atomic Theory:
Aristotle to Rutherford
1. Democritus and Aristotle in 400 B.C.
2. Aristotle: matter can be divided into smaller and
smaller particles.
3. Democritus: the atom is the smallest unit.
4. Aristotle’s theory was most popular.

2. John Dalton’s Contributions...
John Dalton, English school teacher, early 1800’s
(1804) revision of atomic theory and modern model
was begun.
His laws attempted to explain chemical reactions
involve atoms.
1.
Law of conservation of matter
2.
Law of constant composition
3.
All matter made up of atoms
4.
All atoms of a particular element are alike
5. A chemical reaction involves the union or
separation of atoms.

3. United Kingdom

4. The Cavendish Lab, Cambridge, England

5. JJ Thomson and
The Discovery
of The Electron
1. JJ Thomson 1897
2. Crookes Tube
experiment
3. Discovered the
electron.
4. Negative charge

6. JJ Thomson and The Plum Puddling Model
of the Atom
1. JJ Thomson and E.
Goldstein – 1907
2. Discovered the proton.
3. Positive charge.
4. Plum pudding model of
the atom.

7. Ernest Rutherford and
Refining The Atomic Model
1. Ernest Rutherford- 1909
2. Gold foil experiment
3. Alpha particles
4. Revision of the model.

8. The Quantum Mechanic Model: Beyond
The Rutherford Model
1. Quantum Mechanic model: 1910-1930 quantum physics.
2. James Chadwick 1932 discovered the neutron. All these men
did their research at the Cavendish Lab in England.
“That is how science advances: each new conceptual scheme
embraces the phenomena explained by its predecessors and adds
to them… like Aristotelianism before it, Newtonianism at last
evolved---this time within physics---problems and research
techniques which could not be reconciled with the worldview
that produced them.”
---from Thomas Kuhn’s The Copernican Revolution.

9. Unknown
Black Inks
Chromatography
Some Known
Black Inks