1. Chapter 2 Atoms

3. Greek philosopher, Democritus fifth century B.C., coined term atom, as particles that can not be cut or broken up further.

4. Law of Conservation of Mass Antoine Lavosier- found when a reaction occurred in a closed system, total mass of system remained unchanged.

5. Law of Conservation of Mass Matter is neither created nor destroyed during chemical changes. Thus the total mass of the reactants must equal the mass of the products.

6. Law of Definite Proportions Many compounds are made of more than one element Each element has the same proportion in a compound, regardless of where it was made

7. Joseph Proust Copper carbonate from various sources always had same composition Always 36.18% oxygen, 57.48% copper, 5.43% carbon and 0.91% hydrogen

8. Law of Definite Proportions A compound always contains the same elements in certain definite proportions and no other combinations.

9. Atomic Theory of Matter John Dalton-1803- explain data 1.1) All matter made of extremely small particles called atoms 2.All atoms of a given element are alike, but atoms of different atoms are different. 3.Compounds are formed when atoms of different elements combine in fixed proportions.

10. 4. A chemical reaction involves rearrangement of atoms. No atoms are created or destroyed.

11. Modern Modifications 1.Atoms not completely indivisible 2.Not all atoms of an element are completely alike 3.Number of atoms in a molecule usually a simpler ratio

12. Example Jons Berzelius found 10g lead + 1.55g sulfur --- 11.55g Pbsulfate