1. The Quantum Model of the Atom
4-2 Notes
The Quantum Model of the Atom

2. Objectives
Discuss Louis de Broglie’s role in the development of the quantum model of the atom.
Compare and contrast the Bohr model and the quantum model of the atom.
Explain how the Heisenburg uncertainty principle and the Schrodinger wave equation led to the idea of atomic orbitals.
List the four quantum numbers and explain their significance.
Relate the number of sublevels corresponding to each of an atom’s main energy levels, the number of orbitals per sublevel, and the number of orbitals per main energy level.

3. Electrons Exhibit Wave Properties
French Physicist Louis de Broglie decided that every particle of matter is endowed with a wave that will guide as it travels.
Inverse relationship between energy and wavelength
In atoms, electrons move at very high speeds.
They can move at 2 million meters per second.
They are enclosed to a particular energy level, so that they can become synchronized.

4. Electrons Exhibit Wave Properties
The wave nature of electrons is one explanation of how they do NOT spiral close to the nucleus.
They must have specific frequencies at different energy levels.
They exhibit diffraction (bending) and interference (overlap).

5. Heisenberg Uncertainty Principle
Austrian Physicist, Werner Heisenberg, set out to detect electrons in atoms.
Where were they located?
For us to “see” the electron, light photons of an appropriate frequency would have to interact with and bounce off the electron. But such an interaction would transfer energy from the photon to the electron and cause its energy to increase and move faster. And therefore, change its position.

6. Heisenberg Uncertainty Principle
Heisenburg created an uncertainty principle that stated it is impossible to determine simultaneously both the position and velocity of an electron or any other particle.

7. Probability Clouds
There are two ways that scientists help us to visualize electrons.
Probability clouds
Atomic orbitals

8. Probability Clouds
Erwin Shrodinger formed an equation for the intensities of an electron wave to be calculated.
We cannot predict both the speed of an electron and the location at the same time.
However, we can predict where it is most likely to be found.

9. Probability Clouds
If we plot the positions of electrons over time, we find the most likely place for an electron to be.

10. Probability Clouds
The denser the region in the cloud, the more likely an electron would be found there.
The probability cloud is a close approximation of the actual shape of the electron’s 3-D wave.

11. Atomic Orbitals
The atomic orbital shows a specified volume of space, where an electron is most likely to be found, 90% of the time.
Atomic orbitals come in a variety of shapes depending on where the atom is located on the periodic table.

12. Atomic Orbitals

13. Atomic Orbitals

14. Atomic Orbitals

15. Atomic Orbitals

16. Atomic Orbitals
We will be giving each electron in an atom a specific 4 digit number, much like a zip code that we give each different city.
These numbers are called quantum numbers.