1. Introduction to Atomic Structure

2. Dalton’s Atomic Model (early 1800’s) Matter made of atoms Matter made of atoms All atoms of given element are identical All atoms of given element are identical Atoms can combine to form compounds Atoms can combine to form compounds Atoms cannot created nor destroyed just changed Atoms cannot created nor destroyed just changed Chemical reactions Chemical reactions From: A New System of Chemical Philosophy (1808)

3. 3 Atoms Atom = Smallest particle of an element that retains the properties of the element Molecule = Group of atoms that are bonded together and act as a unit 3

4. 4 Plum Pudding Model Discovered electrons (negatively charged particles) in all matter Really small mass Plum Pudding Model Uniformly distributed positive charge Negatively charged particles floating in the positive charge 4

5. Rutherford’s Experiments Gold foil experiment - 1910 α-particles are positive and nuclei are positive => like charges REPEL

6. Rutherford’s Experiments Results according to Plum Pudding Model Actual Results

7. 7 Nuclear Atomic Model Atoms mostly made of empty space Tiny dense region Contains most of the mass Positively charged Electrons held in cloud by attraction 7