1. Orbital Notation, Valence Electrons & Lewis Dot Structures
Get out your notes
Wait quietly

2. Electron Configuration Rules
Aufbau Principle
Each electron MUST occupy the lowest energy orbital available first
Pauli Exclusion Principle
A maximum of 2 electrons can occupy a single orbital, but only if the electrons have opposite spins
Hund’s Rule
Single electrons with the same spin must occupy each equal energy orbital before additional electrons with opposite spins can occupy those same orbitals

3. Aufbau Principle Each electron MUST occupy the lowest energy level and sublevel available first
Determine the order of energy levels, sub-levels, and the orbitals within the sub-levels
Energy levels are in the order of the periods down the periodic table
Order: 1, 2, 3, 4, 5, 6, and 7
Sub-levels: are in the order of s, p, d, and f

4. Notice that d and f sub-levels are “behind” s and p sub-levels
Aufbau Principle:
Notice that d and f sub-levels are “behind” s and p sub-levels

5. Pauli Exclusion Principle A maximum of 2 electrons can occupy a single orbital, but only if the electrons have opposite spins
Remember the amount of orbitals in each sub-level
S-sublevel = 1 orbital = 2 electrons
P-sublevel = 3 orbitals = 6 electrons
D-sublevel = 5 orbitals = 10 electrons
F=sublevel = 7 orbitals = 14 electrons
Each energy level holds a set amount of electrons:
1st energy level = 1 sublevel and 1 orbital = max 2 electrons
2nd & 7th energy level = 2 sublevels and 4 orbitals = max 8 electrons
3rd & 6th energy level = 3 sublevels and 9 orbitals = max 18 electrons
4th – 5th energy levels = 4 sublevels and 16 orbitals = max 32 electrons
Remember that d and f sublevels are behind s and p

6. Hund’s Rule Single electrons with the same spin must occupy each equal energy orbital before additional electrons with opposite spins can occupy those same orbitals
Orbital Notation:
Shows the electrons in an orbital and their spin
S- 1 orbital, p- 3 orbitals, d – 5orbitals, and f – 7 orbitals
Lines/boxes represent the orbitals
The number of the energy level and its sublevel are written below the line
Uses up and down arrows to represent the electrons and their spins
Example: Lithium – 1s22s1
_________ _________
1s s

7. Hund’s Rule Orbital Notation
Let’s Try Nitrogen:
1s22s22p3
___________ _____________ __________ ___________ ___________
1s s p
*This is called an orbital diagram/notation

8. A little more of a challenge: Sulfur
What is Sulfur’s electron configuration?
________________________________________________________
What is Sulfur’s orbital notation?
*Remember:
S- 1 orbital, p- 3 orbitals, d – 5orbitals, and f – 7 orbitals

9. Your Turn: Complete these in your notes
Write the orbital diagrams for the following elements:
Manganese
Potassium
Gallium

10. Valence Electrons
The electrons that determine the chemical properties of an element
The electrons in the highest (outermost) energy level
How do we know what is the highest/outermost energy level?
The electron configuration for Chlorine is:
1s2 2s2 2p6 3s2 3p5
The outermost energy level is the 3rd energy level
Chlorine has 7 valence electrons (2 + 5 = 7)

11. Electron Configuration
Valence Electrons
How many valence electrons are found in the following atoms?
Element
Electron Configuration
# of Valence Electrons
Sodium
Carbon
Gallium
Oxygen
Fluorine

12. Valence Electrons THERE IS AN EASIER WAY!!!!

13. Lewis Dot Structure A model that uses electron-dot structures to show how electrons are arranged in molecules.
Shows the valence electrons around the element symbol
What is an element symbol?
Aluminum =
Aluminum has _____ valence electrons
Imagine aluminum symbol with a box around it
*Each side of the box can only hold 2 electrons
*Put 1 dot (to represent 1 electron) on each side before adding a second dot to that side of the box – Pauli’s Exclusion Principle
So the final product looks like this: Al Al

14. Give Sulfur a try:
How many valence electrons does Sulfur have? ______ S

15. Your turn: Complete these in your notes
Draw the Lewis Dot Structure for the following elements:
Element
Symbol and number of valence electrons
Lewis Dot Structure
Lithium
Nitrogen
Calcium
Bromine
Carbon
Selenium

16. LAB TOMORROW YOU MUST BE DRESSED IN LAB ATTIRE
Until the Bell Rings:
Work on your homework: Page 7 in packet and prelab
REMEMBER:
LAB TOMORROW YOU MUST BE DRESSED IN LAB ATTIRE
Closed shoes
Long pants (no skin, not even ankles)
NO baggie sleeves
Hair pulled back