1. Quantum Mechanics n n = The principle quantum number Describes the possible energy levels and pictorially it describes the orbital size. n = 1, 2, 3…. where an energy level with the value of 2 is larger than one with the value of 1. 1s 2s

2. Quantum Mechanics l l = angular momentum quantum number Describes the "shape" of the orbital and can have values from 0 to n - 1 for each n. orbital designation :s p d f shape : m l = magnetic quantum number l ll Related to the orientation of an orbital in space relative to the other orbitals with the same l quantum numbers. It can have values between l and - l. m s = spin quantum number An electron has either + 1 / 2 or - 1 / 2 spin values; sometimes referred to as spin up and spin down. Too hard to draw see text

3. Orbital Shapes

4. Electron Configuration Electron configuration is a shorthand notation for describing the arrangement of the electrons about the nucleus. General Format using the quantum numbers: n l e- n l e- RULES: 1. Fill the lowest energy levels first. 1s 2s 2p 3s 3p 4s 3d 4p 2. No more than two electrons per orbital. n = principle quantum number l = angular momentum quantum number e- = number of electrons Lowest

5. Electron ConfigurationExamples: H:He:Li : H:1s 1 He:1s 2 Li : 1s 2 2s 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 7 Co: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 7 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 Br: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 CORE VALENCE The condensed electron configuration distinguishes the core electrons from the valence electrons. CORE electrons are tightly held to the nucleus and resemble a noble gas configuration. VALENCE electrons are the outer most electrons and are involved in chemical reactions. Examples of the condensed configuration: 3d 7 Li:[He] 2s 1 Co:[Ar] 4s 2 3d 7 3d 10 4p 5 Br:[Ar] 4s 2 3d 10 4p 5

6. Electron Configuration Practice Problems 1. Give the full electron configuration: C ONe Na Si Cl Ar K 2. Give the condensed electron configuration: C ONe Na Si Cl Ar K Answers on next slide

7. Electron Configuration Answers 1 & 2. Give the full & condensed electron configuration: C 1s 2 2s 2 2p 2 or [He] 2s 2 2p 2 O 1s 2 2s 2 2p 4 or [He] 2s 2 2p 2 Ne 1s 2 2s 2 2p 6 or [Ne] Na 1s 2 2s 2 2p 6 3s 1 or [Ne] 3s 1 Si 1s 2 2s 2 2p 6 3s 2 3p 2 or [Ne] 3s 2 3p 2 Cl 1s 2 2s 2 2p 6 3s 2 3p 5 or [Ne] 3s 2 3p 5 Ar 1s 2 2s 2 2p 6 3s 2 3p 6 or [Ar] K 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 or [Ar]4s 1

8. Orbital Diagrams RULES: 1.Aufbau Principle – electrons fill the lowest energy level first 2.Hunds Rule – electrons fill each orbital in a subshell with one electron first before they double up. 3.Pauli Exclusion Principle – no two electrons can have the same four quantum numbers

9. Orbital Diagrams 4p ___ ___ ___ 3d ___ ___ ___ ___ ___ 4s ___ 3p ___ ___ ___ 3s ___ 2p ___ ___ ___ 2s ___ 1s ___ Aufbau Principle Hunds Rule Pauli Exclusion Principle

10. Orbital Diagrams Practice Problems 1. Draw orbital diagrams for: C ONe Na Si Cl Ar K