atomos

1. The Atom

2. Objectives
 Describe how the structure of atom developed
 Recognize the importance of John Dalton’s atomic
theory
 Preserve the contribution of others

3. The Atom
 smallest unit of matter
 make up everything
 2000 years of understanding

4. Atomic History

5. Empedocles
 four elements

6. Aristotle
 added one element
•aether

7. Democritus
 objects made of small particles
 “Atomism”
 Atomos- indivisible

8. John Dalton
 1803
 atoms as indestructible spheres
 uniform in shape

9. Dalton’s Atomic Theory
 All matter is made up of indivisible particles called atoms.
 All atoms of a given element are identical in mass and properties,
and different from atoms of other elements.
 Atoms of different elements contain different mass.
 Two or more different types atoms combine to form compounds.
 Chemical reaction is the rearrangement, separation, or
combination of atoms.

10. Joseph Thomson
 discovered (-) particles
•embedded in (+) core
 atoms are not indivisible

11. Ernest Rutherford
 atoms have a nucleus
•dense (+) core
•surrounded by electrons

12. Neils Bohr
 electrons revolve in orbits
•does not use energy
•jump depending on energy

13. Atomic Structure