1. Atomic Theory

2. How to take notes today:
For each scientist:
Write the green items in Dates
Write the blue and red in Theory and Facts
Draw a pic of there model
You only need to write the colored information.

3. First Concept of an Atom

4. John Dalton 1766-1844 Introduced his ideas in 1803
Each element is composed of extremely small particles called atoms
All the atoms of a given element are identical, but they differ from those of any other element
Atoms are neither created nor destroyed in any chemical reaction
A given compound always has the same relative numbers and kinds of atoms
John Dalton

5. Dalton’s Model

6. J.J. Thompson
Discovered electron 1897 – Cathode Ray Experiment
Plum Pudding model 1904
Electrons discovered in a soup of positive charges
Discovered isotopes 1913

7. JJ Thompson’s Ideas

8. Cathode Ray Tube Experiment

9. Plum Pudding Model

10. Ernest Rutherford 1871-1937 Nucleus Theory 1910
alpha particle gold foil experiment
An atom’s mass is mostly in the nucleus
The nucleus has a positive charge (Moseley)
Electrons in fixed orbit

11. Gold Foil Experiment

12. Rutherford Model

13. Niels Bohr 1885-1962 Planetary Model 1913
Nucleus surrounded by orbiting electrons at different energy levels
Electrons have definite orbits
Utilized Planck’s Quantum Energy theory
Worked on the Manhattan Project (US atomic bomb)

14. Bohr’s Model

15. Bohr Model for Nitrogen

16. Quantum Mechanical Model 1926
Ernst Schrödinger
Werner Heisenberg
Quantum Mechanical Model 1926
Electrons are in probability zones called “orbitals”, not orbits and the location cannot be pinpointed
Electrons are particles and waves at the same time
Developed quantum numbers based on theories of Einstein and Planck

17. Orbital model

18. Quantum Mechanical Theory Electron in a Hydrogen atom

19. In 1869, created a periodic table we still use today
Dmitri Mendeleev
In 1869, created a periodic table we still use today
elements were ordered by atomic weight and placed in groups based on their chemical properties.
Mendeleev's decision to design
the periodic table in this way
allowed immediate advances in chemistry by predicting the properties of undiscovered elements in specific atomic weight ranges.

20. Dmitri Mendeleev’s Periodic Table