1. Laws of Matter & Dalton’s Atomic Theory Reviving the Ancient Idea

2. Review of Lavoisier Defined what an element was. Proposed program for chemistry. Discovered conservation of mass.

3. What’s Next? Quite clear that Aristotle was incorrect. But, what then was the world made up of? Elements? But, what then were elements made up of?

4. Fortunately, advancements in instrumentation led to more precise balances and …

5. Other Laws Discovered Law of Definite Proportions Law of Multiple Proportions In addition to the Gas Laws and Conservation of Mass

6. Which law does this picture illustrate? Gold element = 1.00 g Green element = 0.80 g Gold element = 1.00 g Green element = 2.40 g Gold element = 1.00 g Green element = 1.60 g

7. Hydrogen gas (2.02g) + Oxygen gas 16.00g = Water 18.02 Which law does this picture illustrate?

8. Manufactured in a lab 50% oxygen by mass 50% sulfur by mass Mined out of the ground 50% oxygen by mass 50% sulfur by mass

9. Which law does this picture illustrate? Balloon at room temperature Balloon heated up

10. The Atom becomes a theory These developments led John Dalton to revive Democritus’ idea of the atom and create a theory of his own.

11. Dalton’s Atomic Theory 1. All matter is made of extremely small particles called atoms (in constant motion). 2. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. 3. Atoms cannot be subdivided, created, or destroyed. 4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds. 5. In chemical reactions, atoms are combined, separated, or rearranged.

12. Conservation of mass Point 3: Atoms cannot be subdivided, created, or destroyed. Point 4: In chemical reactions, atoms are combined, separated, or rearranged.

13. Gas Laws Point 1: All matter is made of extremely small particles called atoms (in constant motion).

14. Law of definite proportions Point 2: Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.

15. Law of multiple proportions Point 4: Atoms of different elements combine in simple whole-number ratios to form chemical compounds.

16. Theory Accepted Dalton’s theory was accepted because it explained what was seen. But, it did not give a way to determine molecule formulas.  How two atoms came together and in what ratios to form compounds.  Dalton knew water was a 1 to 8 ratio by mass but thought the molecular formula was HO.

17. Matter Pure SubstanceMixture Element Compound HomogenousHeterogeneous Ex. Air Ex. GraniteEx. WaterEx. Iron Basic unit: Molecule Basic unit: Atom Can it be separated physically? NoYes No Uniform? Chemically separated?