1. John Daltons Atomic Theory All matter is composed of small particles called atoms All atoms of a given element are a like Compounds are formed when different atoms combine in fixed proportions A chemical reaction involves the rearrangement of atoms

2. Development of the Atom John Dalton - Produced the first atomic theory Taught that atoms were hard round spheres

4. Development of the Atom John Dalton (1803) - Produced the first atomic theory Taught that atoms were hard round spheres Michael Faraday (1825)- Split compounds by electrolysis and showed that atoms have electrical properties

5. Ions - Charged atoms Cation - positive charged atom Anion - negative charged atom

6. Development of the Atom John Dalton - Produced the first atomic theory Taught that atoms were hard round spheres Michael Faraday - Split compounds by electrolysis and showed that atoms have electrical properties Joseph John Thompson - Used cathode ray tube to discover the negative charged electron and the mass to charge ration on the electron

7. Development of the Atom John Dalton - Produced the first atomic theory Taught that atoms were hard round spheres Michael Faraday - Split compounds by electrolysis and showed that atoms have electrical properties Joseph John Thompson - Used cathode ray tube to discover the negative charged electron and the mass to charge ratio on the electron Eugene Goldstein - Discovered the proton. Found mass to be 1837 time the electron and + charged

9. Development of the Atom Joseph John Thompson - Used cathode ray tube to discover the negative charged electron and the mass to charge ratio on the electron Eugene Goldstein - Discovered the proton. Found mass to be 1837 time the electron and + charged Robert Millkan - Determined the electron charge, using oil drop experiment

11. Development of the Atom Eugene Goldstein - Discovered the proton. Found mass to be 1837 time the electron and + charged Robert Millkan - Determined the electron charge Dmitri Mendeleev - Father of the periodic table – predicted that his unfilled table represented undiscovered elements

12. Other Contributors Wilhelm (Conrad) Roentgen – X-Ray’s Henri Becquerel – Radioactivity Marie Curi – Intensity of Radioactivity