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John Dalton's Model | Joseph John Thomson Model | Rutherford | Bohr Model | Quantum Model
The History of the Atom

"We might as well attempt to introduce a new planet into the solar system, or to annihilate one already in existence, as to create or destroy a particle of hydrogen."
-John Dalton (A New System of Chemical Philosophy, 1808)

Welcome to the web site dedicated to education regarding the history of the discovery of the atom and the evolution of atomic theory. From ancient Greek times of philosophy to today's technological era of quantum physics, scientists have been mesmerized by what is thought to be the smallest particle - the atom. In Greek, the prefix "a" means "not" and the word "tomos" means cut. Thus, atomos or atom means uncuttable or undividable.

Browse the site and learn about what theories have shaped how we view molecules and matter on Earth.

Greek Beginnings

The concept of the smallest particle was concieved in the 5th centruy BC by Leucippus of Miletus. His pupil, Democritus of Abdera developed five major points that their theory was based upon. Historians have discovered this from the quotations of other Greeks (most of the original documents by Leucippus and Democritus have been lost). In the 4th centruy BC, the well known philosopher Aristotle vehemetly argued that the atomic theory was completely incorrect and was therefore dismissed by scientists for many decades. In fact, the Catholic Church agreed with Aristotle's position and annouced that atomistic ideas were equivalent to those of Godlessness. "Democritus of Abdera said that there is no end to the universe, since it was not created by any outside power."

The 5 points of their conclusion are as follows...

Point #1 - All matter is made up of undividable particles called atoms.

Point #2 - There is a void, which is empty space between atoms.

Point #3 - Atoms are completely solid.

Point #4 - Atoms are homogeneous, with no internal structure.

Point #5 - Atoms vary in
1) Size
2) Shape.
3) Weight

Graphic of books; Actual Size=130 pixels wide

This Site was a project assigned August
24, 2001. It is due today, August 31,

Mr. Aboulafia's 1st period Honors
Chemistry Class
By: George Stamps

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