1. History of Atom Flip Book • The atom • Picture, parts including charge and location • Chadwick • Discovered the… • Rutherford • Gold Foil Experiment • JJ Thomson • Cathode Ray Tube • Millikan • Oil Drop experiment • Dalton • Dalton’s Atomic Theory • Democritus • His 5 ideas • Aristotle • Link with nature (Figure 4-1)

2. History of the atoms • Matter is composed of empty space through which atoms move • Atoms are solid, homogeneous, indestructible, and indivisible • Different kinds of atoms have different sizes and shapes • Differing properties are due to the size, shape and movement of atoms • Changes in matter result from the changes in groupings of atoms • Matter is composed of air, fire, water, and Earth • His popularity allowed his ideas to persist into the 1800’s.

3. Dalton’s Atomic theory • All matter is composed of extremely small particles called atoms • All atoms of a given element are identical • Atoms can not be created, divided, or destroyed (Law of Conservation of Mass) • Different atoms combine in simple whole number ratios to form compounds (Law of Definite Proportions) • In a chemical reaction, atoms are separated, combined, or rearranged Unlike Democritus, Dalton proved his ideas with science experiments.

4. Subatomic Particles • JJ Thomson • Found charge to mass ratio of electron • Proved atoms were divisible into smaller subatomic particles—Big Shock to Science Community • Cathode Ray Tube • Would later create the Plum Pudding Model

5. Subatomic Particles • Millikan • Oil drop experiment • Found the charge of one electron • Electron charge = 1.602x10-19 coulombs • Accepted as -1 charge

6. Subatomic Particles • Ernest Rutherford • Gold Foil Experiment • Shoot positive particles at gold foil

7. Subatomic Particles • Ernest Rutherford • Gold Foil Experiment • Found that most positive shots went straight through but some bounced back • Atom was largely empty space through which electrons moved • Atoms contained tiny dense region called a nucleus that contained most of the mass An atom the size of two football fields would have a nucleus the size of a nickel

8. Subatomic Particles • Chadwick • Discovered the neutrons • Neutrons act to separate the + protons so that they don’t repel each other

9. Atom Smallest particle of an element that retains the properties of the element