- 440 B.C, a Greek philosopher came up with the concept of the atom
- said that atoms were small, hard particles that could not be divided("Uncuttable")
- said that there was no way to separate them
- Atomic Theory
- All substances are made of atoms. Atoms are small particles that cannot be created, divided, or destroyed.Atoms of the same element are exactly alike and atoms of different atoms are different.Atoms join with other atoms to make new substances
- Found Electrons
- experimented with a Cathode-Ray Tube
- called the negative charged particles corpuscles- electrons.
- Plum Pudding model showed a possible structure of the atom with the negative charges.
- discovered that the atom had a small, dense nucleus than contained positive charges.
- Gold foil experiment- a mined charged particles at a thin sheet of gold foil.
- "Planetary Model"
- determined that electrons traveled around the nucleus in definite paths.
- also discovered that electrons could jump from a path in one level to a path in another level
Schrodinger and Heisenberg
- explained that electrons do not travel in definite paths.
- Electron paths cannot be predicted.
- The current theory suggests that electrons are found in the regions called election clouds.