1. Atomic Structure

2. What is an Atom? The smallest part of an element.

3. Early models of the atom: Democritus: Matter is made of tiny indivisible and indestructible particles called atoms. IT’S ALL GREEK TO ME... 460-370 BC

4. John Dalton - 1803 Atom is indivisible. All atoms of a given element are identical. Conservation of atoms in a chemical reaction.

5. 1.ALL MATTER IS COMPOSED OF EXTREMELY SMALL PARTICLES CALLED ATOMS 2.ATOMS OF A GIVEN ELEMENT ARE IDENTICAL IN SIZE, MASS, AND OTHER PROPERTIES; ATOMS OF DIFFERENT ELEMENTS DIFFER IN SIZE, MASS, & OTHER PROPERTIES ELEMENT 1 ELEMENT 1 ELEMENT 2 ELEMENT 2 ELEMENT 3 ELEMENT 3 ELEMENT 4 ELEMENT 4

6. 3.ATOMS CAN NOT BE CREATED OR DESTROYED 4.ATOMS OF DIFFERENT ELEMENTS COMBINE IN SIMPLE WHOLE # RATIOS TO FORM CHEMICAL COMPDS. 5.IN CHEMICAL REACTIONS, ATOMS ARE COMBINED, SEPARATED, OR REARRANGED ++++

7. Static Electricity 1750’s Ben Franklin studied charges. Two types: Positive and Negative Static Electricity Commercial

8. THE FIRST DISCOVERY OF A SUBATOMIC PARTICLE RESULTED FROM THE INVESTIGATIONS INTO THE RELATIONSHIP BETWEEN ELECTRICITY AND MATTER. IN THE LATE 1800’S, MANY EXPERIMENTS WERE PERFORMED IN WHICH ELECTRIC CURRENT WAS PASSED THROUGH VARIOUS GASES AT LOW PRESSURE. CARRIED OUT IN TUBES CALLED CATHODE-RAY TUBES THE FIRST DISCOVERY OF A SUBATOMIC PARTICLE RESULTED FROM THE INVESTIGATIONS INTO THE RELATIONSHIP BETWEEN ELECTRICITY AND MATTER. IN THE LATE 1800’S, MANY EXPERIMENTS WERE PERFORMED IN WHICH ELECTRIC CURRENT WAS PASSED THROUGH VARIOUS GASES AT LOW PRESSURE. CARRIED OUT IN TUBES CALLED CATHODE-RAY TUBES

9. INVESTIGATORS NOTICED THAT WHEN CURRENT WAS PASSED THROUGH A CATHODE RAY TUBE, THE SURFACE OF THE TUBE DIRECTLY OPPOSITE THE CATHODE GLOWED. Cathode Ray Video

10. J.J. Thomson 1856-1940 I PLAY WITH ELECTRONS THOMPSON CONCLUDED THAT ALL CATHODE RAYS ARE COMPOSED OF IDENTICAL NEGATIVELY CHARGED PARTICLES LATER WERE CALLED ELECTRONS.

11. J.J. Thomson Discovered electron “Plum Pudding Model”

12. Ernest Rutherford - 1909 HOW IS THE ATOM BUILT? Gold Foil Experiment

13. Ernest Rutherford Gold Foil Experiment: Dense (+) charge nucleus Electrons orbiting on outside Atom is mostly empty space