1. Atomic Theory

2. Let’s Take a Trip Through Time!

3. Democritus 460 – 370 B.C.
There are various basic elements from which all matter is made
Everything is composed of small atoms moving in a __________
Ideas rejected by leading philosophers because void ______________________

4. First Concept of an Atom

5. Aristotle ____________ Democritus’ theory
Stated that matter is _____________________________
This was the theory that was accepted for _______________________________

6. John Dalton 1766-1844 Introduced his ideas in 1803
1. All matter is composed of ________________________________________________________
2. All the atoms of a given element _____________________________________________________but ________________________________________________________
3. Atoms are ________________________________________________in any chemical reaction
4. A given compound ___________________________________________________________________________________

7. Dalton’s Model

8. J.J. Thomson 1856-1940 Discovered electron 1897 – _____________
____________________
Plum Pudding model 1904
Electrons in a _______ of positive charges
Discovered isotopes 1913

9. Plum Pudding Model

10. Ernest Rutherford 1871-1937 Nucleus Theory 1910 An _________________
__________________________________________
An _________________
_____________________
The nucleus has a positive charge (Moseley)
Electrons in empty space.

11. Alpha Particle Experiment

12. Rutherford Model

13. Niels Bohr 1885-1962 Planetary Model 1913
Nucleus surrounded by orbiting electrons at_______
__________________________
Electrons have ____________
Utilized Planck’s Quantum Energy theory
Worked on the Manhattan Project (US atomic bomb)

14. Bohr’s Model

15. Bohr Model for Nitrogen

16. Ernst Schrödinger 1887-1961 Werner Heisenberg 1901-1976
Quantum Mechanical Model 1926
Electrons are in ___________
_________ called ____________ not orbits and the location cannot be pinpointed
Electrons are _____________
___________________________
Developed quantum numbers based on theories of Einstein and Planck

17. Orbitals