1. Electron Configurations
Day 1 - Notes
Electron Configurations
Introduction to Quantum Mechanical Model

2. After today you will be able to…
Explain the organization of electrons within an atom
Describe what an energy level, sublevel, and atomic orbital is
Draw the shapes of each sublevel
Predict how many electrons can be held in each energy level

3. The Quantum Mechanical Model of electrons within an atom says we cannot pinpoint where an electron is, but we can get the probability of where the electron is.
Electron configurations show how electrons are distributed within an atom.

4. YOU COULDN’T HANDLE THE TRUTH! 
Remember when. . . ?
You envisioned an atom having a single center and “rings” around that center?
However… that wasn’t the whole truth.
YOU COULDN’T HANDLE THE TRUTH! 

5. Principal Energy Levels
n=1,2,3,4, etc.
Describes the average distance of an electron from the nucleus
Energy increases as you move further from the nucleus
n=2
n=1
Nucleus
e-s highest in energy
e-s lowest in energy

6. Within each energy level, electrons occupy sublevels.

7. Sublevels
Correspond to the different areas an electron can be located in an atom.
Represented by a letter
Example: s, p, d, f, g, h, i, etc.

8. Sublevel Types s sublevel: “spherical” p sublevel: “dumbbell”
d sublevel: “clover”
f sublevel: “double clover”

9. Types of Sublevels in Energy Levels1 1s 2
2s 2p 3
3s 3p 3d 4
4s 4p 4d 4f 5
5s 5p 5d 5f (5g)

10. Atomic Orbitals
Each sublevel is oriented differently in 3-D space, and each orientation is called an atomic orbital
Atomic orbitals can hold only two electrons

11. # of Atomic Orbitals in Sublevels
Type of Sublevel
# of Atomic Orbitals
# of Electrons in sublevel s 1 2 p 3 6 d 5 10 f 7 14 [g 9
18]

12. (See sublevel shape diagram handout.)
Orbitals for a particular sublevel are similar in shape, but different in orientation and size.
(See sublevel shape diagram handout.)

13. # of Electrons in Each Energy Level
# of Electrons in an Energy Level 1 s 2
s p
2 + 6 = 8 3
s p d
= 18 4
s p d f
= 32

14. In general… s < p < d < f in energy within an energy level
Electrons prefer to occupy the orbitals that require the least amount of energy

15. Questions?
Complete WS 1