3. (1734 – 1794) The Father of Modern Chemistry
Antoine Lavoisier
(1734 – 1794)
The Father of Modern Chemistry

4. Experiments Did a similar exp. to steel wool exp.
Heated tin in a sealed flask. It removed 1/5 of the air.
Conclusion: Gas combined with tin.
Repeated the exp. with mercury
Reverse of what Priestley did
Same thing happened
Communicated with Priestley

5. Conclusions
Priestley’s new gas (oxygen) was combining with the metals.
Combustion and rusting are processes where a substance combines with oxygen.
1/5 of air is oxygen & 4/5 is an inert gas, nitrogen.

6. Other Contributions Showed that metals gain mass when burned
Discovered law of conservation of mass
In a chemical reaction, nothing is created or destroyed.
Proposed program for chemistry
Find elements, their weights, and rules of combination
By 1800, 30 elements were discovered

7. Reasons for Lavoisier’s Success
Workable definition of an element
A substance that can not be reduced in weight by any chemical reaction
Carefully accounted for all substances going into and out of chemical reactions by tracking their weights.

8. Classification of Matter
Yes No
Can it be separated
physically?
Mixture
Pure Substances
Is it uniform in composition?
Yes No
Yes
Can it be separated
chemically? No
Homogenous
Heterogeneous
Compound
Element
Ex. Salt water
Ex. Salad
Ex. H2O
Ex. Mercury