1. Electron Configuration

2. The Bohr Model of the Atom
I pictured electrons orbiting the nucleus much like planets orbiting the sun.
But I was wrong! They’re more like bees around a hive.
Neils Bohr

3. Heisenberg Uncertainty Principle
“One cannot simultaneously determine both the position and momentum of an electron.”
You can find out where the electron is, but not where it is going.
OR…
You can find out where the electron is going, but not where it is!
Werner
Heisenberg

4. Electron Energy Level (Shell)
Generally symbolized by n, the energy level tells us the distance of the electron from the nucleus. “n” is also known as the Principle Quantum number
Number of electrons that can fit in a shell:
2n2

5. Electron review
Electrons are found outside the nucleus in orbitals/ shells For an atom to be happy and not need to bond with anything else it must have 8 e- in the outer shell (except H and He which only have 1 shell they need 2). If they +/- electrons they are ions.

6. Electron Orbitals
An orbital is a region within an energy level where there is a probability of finding an electron.
Orbital shapes are defined as the surface that contains 90% of the total electron probability.

7. Rules
There are specific rules for the way in which electrons behave- Electron Configuration
What rules do we have
Pauli Exclusion Principle
Hund’s Rule
Aufbau Principle

8. There are 4 sub-orbitals S,P,D,F
There are 4 orbitals S,P,D,F
There are 4 sub-orbitals S,P,D,F
S-2,P-6,D-10,F-14

9. s Orbital shape The s orbital has a spherical shape centered around
the origin of the three axes in space.

10. p orbital shape
There are three dumbbell-shaped p orbitals in each energy level above n = 1, each assigned to its own axis (x, y and z) in space.

11. d orbital shapes
Things get a bit more complicated with the five d orbitals that are found in the d sublevels beginning with n = 3. To remember the shapes, think of “double dumbells”
…and a “dumbell
with a donut”!

12. Shape of f orbitals

13. Orbital filling table

14. Pauli Exclusion Principle
Two electrons occupying the same orbital must have opposite spins
(represented by up arrow
or down arrow)
Wolfgang
Pauli

17. Hund’s Rule For and atom in the ground state:
Fill each orbital before pairing electrons together
The electrons must have the same spin when initially filling the orbital ( fill up arrows first then down arrows)

19. Aufbau Principle
Each electron must occupy the lowest energy level first
S must be filled before beginning P. P must be filled before D and so on.

20. How would we write the electron configuration for sulfur?
Practice
How would we write the electron configuration for sulfur?
1s22s22p63s23p4
How many electrons are represented in the electron configuration?
16…. And sulfur has 16 electrons