1. From Philosophical Idea to Scientific Theory
The Atom:
From Philosophical Idea to Scientific Theory

2. Particle Theory of Matter
Dates back to 400 B.C. and Greek philosophers like Democritus
Coined the term “atom” which meant “indivisible”

3. Experiments Advance
In the 18th century several basic scientific laws develop.

4. Law of Conservation of Mass
Mass is neither created nor destroyed during normal chemical reactions.

5. Law of Definite Proportions
A chemical compound contains the same elements in the same proportions regardless of sample size or source.

6. Law of Multiple Proportions
If two or more different compounds are composed of the same two elements then ratios of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.

7. John Dalton
In 1808 an English schoolteacher proposed an explanation for the 3 basic laws.
This became known as the Atomic Theory

8. Dalton’s Atomic Theory
All matter is composed of particles called atoms
Atoms of a given element are identical in size, mass and other properties. Atoms of different elements differ in size, mass and other properties.

9. Dalton’s Atomic Theory
Atoms cannot be subdivided, created or destroyed
Atoms of different elements combine in simple, whole number ratios to form chemical compounds.
In chemical reactions, atoms are combined, separated or rearranged.

10. Modern Atomic Theory
As technology improved and more information became available Dalton’s theory has become modified.

11. Modern Atomic Theory Two basic tenets remain:
All matter is composed of atoms
Atoms of one element differ in properties from atoms of another element.

12. Assignment Read pages 65-68 Answer the following:
Name the various compounds that the carbon atom was a component of in Levi’s story.
Why was it unlikely for the carbon atom to have been taken into the bird’s bloodstream?
Section Review pg. 69 (1-3)