1. Atoms: PAGE 37 OF INB

2. Essential Question  How are Dalton’s atomic theory and modern atomic theory similar and different?

3. Early Thoughts on Atoms  Democritus: (400 B.C.) Idea of atom. An indivisible particle that makes up everything.  Aristotle: did not believe in atoms, believed all matter was continuous.  Accepted for nearly 2000 years.

4. Foundation of Atomic Theory.  1700’s accepted modern definition of an element.  A substance that can not be further broken down by ordinary chemical means.  Elements combine to form new compounds with different chemical and physical properties. (a chemical Reaction)

5. Some laws  Law of conservation of mass:  Law of definite Proportions:  Law of multiple proportions:

6. Dalton’s Atomic Theory: 1) All matter is composed of extremely small particles called atoms 2) Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements are different in size, mass, and other properties. 3) Atoms can not be subdivided, created or destroyed.

7. Dalton’s Atomic Theory (CON’T) 4)Atoms combine in simple whole- number ratios to form chemical compounds. 5)In chemical reactions, atoms are combined, separated, and rearranged.

8. Modern Atomic Theory 1) All matter is composed atoms 2) Atoms of Different elements are different in size, mass, and other properties. 3)Disproven (they are dividable). 4)Law of Multiple proportions 5)Law of conservation of mass.