1. ELECTRON DISTRIBUTION LAB

3. ELECTRON CONFIGURATIONS

4. WHAT IS AN ELECTRON CONFIGURATION? The arrangement of electrons in an atom

5. THREE RULES TO REMEMBER… 1. Aufbau Principle 2. Pauli Exclusion Principle 3. Hund’s Rule

6. AUFBAU PRINCIPLE States that each electron occupies the lowest energy orbital available Must learn the sequence of atomic orbitals from lowest energy to highest energy Called the Aufbau diagram! Each box represents an atomic orbital

8. HOW TO REMEMBER THE AUFBAU PRINCIPLE Principal quantum numbers are like floors of a hotel e- enters the lowest level first

9. PAULI EXCLUSION PRINCIPLE Electrons in orbitals can be represented by arrows in boxes. Every electron has an associated spin Can only spin two ways Represents electron spinning in one direction Represents electron spinning in opposite direction Represents unoccupied orbital Represents a filled orbital Pauli Exclusion Principle States that a maximum of TWO electrons can occupy a single atomic orbital, but only if they have opposite spins.

10. HOW TO REMEMBER THE PAULI EXCLUSION PRINCIPLE Spin one index finger away from you Spin the other index finger toward you

11. HUND’S RULE Single electrons with the same spin must occupy each equal energy orbital before additional electrons with opposite spins can occupy the same orbital. How to Remember…. Strangers on a Bus! Do you sit next to a stranger… or pick an empty seat? Pick an empty seat, unless there isn’t one, then you sit with the stranger…

13. Orbital Diagram for Phosphorus

14. ORBITAL DIAGRAMS CONT. Draw the orbital diagram for Sodium Chlorine

15. ORBITAL & ELECTRON CONFIGURATION NOTATION

16. ELECTRON CONFIGURATION NOTATION 1s 2s 2p 3s 3p 3d 4s 4p 4d 5f 5s 5p 5d 5f 6s 6p 6d 7s 7f Remember 1 s-orbital 3 p-orbitals 5 d-orbitals 7 f-orbitals Silicon