Mastering Electron Configurations and Aufbau Principle in Chemistry

1. Bell Work • PRE-AP ONLY: Draw an Aufbau Chart. • Write the Electron Configuration for • H • LI • P • Fe • What does the Aufbau Principle say?

2. What You Should Know How to Do • Aufbau Chart: • Pre-AP Draw & Read • Chem I Read • Write Electron Configurations • State Aufbau Principle

4. Spherical Radii of the Orbitals

5. Pauli Exclusion Principle • Electrons are subject to the Pauli Exclusion Principle, so: No electron can occupy the same quantum state as another • So, how do 2 electrons occupy the same energy level and orbital?

6. Pauli Exclusion Principle • They have “spin” • electrons in the same orbital will have different “spins” • An analogy is to think of it as clockwise and counterclockwise spinning • These spins are called “up” spin and “down” spin • They are written as

7. Hund’s Rule • Each sub-orbital will have 1 electron before any get a second • Two ways to think of it • The Candy Rule – it’s not fair if some get 2 pieces of candy and some get none, first everyone gets a piece, then we start handing out a second piece • The Urinal Rule

8. Hund’s Rule • Two ways to think of it • The Candy Rule – it’s not fair if some get 2 pieces of candy and some get none, first everyone gets a piece, then we start handing out a second piece • The Urinal Rule (for the guys) – no “pairing” until you have to

11. Which is Correct?

12. Class Work • Show Hund’s Rule for: • H • He • C • F • Write the electron configuration for H, N, Na, Cl, K, V, Cu, Se, Kr, Y

13. Exit Ticket • Draw Hund’s Rule for: • Li • Ne • Write the electron configuration for: • B • Al • Ga