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

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

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.

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

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.

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