1. Quantum Model of the Atom
Bohr
de Broglie
Heisenberg
Schrödinger

2. Bohr Model of the Hydrogen Atom –
Neils Bohr (1885 –1962)
Bohr Model of the Hydrogen Atom –
Worked with Einstein & Plank, deciding photons were more like particles that could be measured.

3. Bohr model of the atom
In the Bohr model, electrons can only exist at specific energy levels (orbit).
Energy

4. Photo Absorption and Emission

5. Specifically, Ephoton = E2 - E1 = h 
Line Spectra
Line spectrum of Hydrogen is produced when an electron drops from a higher-energy orbit to a lower energy orbit.
Specifically, Ephoton = E2 - E1 = h 

6. Bohr Checked it with Math.
Used mass and charge of the electron together with Plank’s constant and calculated where the spectral lines should be and they were!
Problem -- only worked for Hydrogen!

8. Problems! “Classical” theory says no.
Hydrogen should be excited by whatever amount of energy.
Should be continuous spectrum
What’s with the lines????

9. Why wouldn’t there be an infinite number of energy levels for electrons?
Unable to account for these questions but was the fist to observe the Photoelectric effect and Hydrogen spectrum.

10. Louis de Broglie ( )
Electrons should be considered waves confined to the space around an atomic nucleus

11. The Quantum Atom (cont.)
Since electrons are waves, they can amplify and cancel out when in and out of sync.
Therefore only certain energies of electrons are possible.

12. Werner Heisenberg
Heisenberg Uncertainty Principle – It is impossible to determine the position and velocity of an electron simultaneously.

13. Heisenberg uncertainty principle
In order to observe an electron, one would need to hit it with photons having a very short wavelength.
Short wavelength photons would have a high frequency and a great deal of energy.

14. Heisenberg uncertainty principle
If one were to hit an electron, it would cause the motion and the speed of the electron to change.
Lower energy photons would have a smaller effect but would not give precise information.

15. Erwin Schrödinger ( )
Schrödinger developed the calculus to describe the wave behavior and energies of electrons in atoms.

16. Schrödinger’s Equation
Yeah, but it works!

17. Bohr vs. Schrödinger Orbits vs. Orbitals
Bohr -- definite distinct orbits populated by electron particles.

18. Bohr vs. Schrödinger Orbits vs. Orbitals
Schrödinger -- electron are waves (de Broglie) with a certain probability (mathematical model) of being found in three dimensional regions around the nucleus - orbitals

19. Orbitals
Distinct area within the atom, where there is a high probability of finding an electron.
The denser the orbital, the higher the probability.