n = The principle quantum number Quantum Mechanics In quantum mechanics, the electrons occupy specific energy levels (as in Bohr's model) but they also exist within specific probability volumes called orbitals with specific orientations in space. The electrons within each orbital has a distinct spin. n = The principle quantum number Describes the possible energy levels and pictorially it describes the orbital size. n = 1, 2, 3…. where an orbital with the value of 2 is larger than an orbital with the value of 1. 2s 1s

Quantum Mechanics 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 : ml = magnetic quantum number 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 . ms = 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

Orbital Shapes

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- 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

Electron Configuration Examples: H : 1s1 He: 1s2 Li : 1s2 2s1 Co: 1s2 2s2 2p6 3s2 3p6 4s2 3d7 Br: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 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: Li:[He] 2s1 Co:[Ar] 4s2 3d7 Br:[Ar] 4s2 3d10 4p5

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

Electron Configuration Answers 1 & 2. Give the full & condensed electron configuration: C 1s2 2s2 2p2 or [He] 2s2 2p2 O 1s2 2s2 2p4 or [He] 2s2 2p2 Ne 1s2 2s2 2p6 or [Ne] Na 1s2 2s2 2p6 3s1 or [Ne] 3s1 Si 1s2 2s2 2p6 3s2 3p2 or [Ne] 3s2 3p2 Cl 1s2 2s2 2p6 3s2 3p5 or [Ne] 3s2 3p5 Ar 1s2 2s2 2p6 3s2 3p6 or [Ar] K 1s2 2s2 2p6 3s2 3p6 4s1 or [Ar]4s1

Orbital Diagrams ___ ___ ___ 4p ___ ___ ___ ___ ___ 3d ___ 4s Orbital diagrams are written in order of increasing energy levels starting with the lowest energy level the 1s orbital. ___ ___ ___ 4p ___ ___ ___ ___ ___ 3d ___ 4s ___ ___ ___ 3p ___ 3s ___ ___ ___ 2p ___ 2s ___ 1s RULES: (1) fill the lowest energy level first (2) fill each orbital in a subshell with one electron first before you double up. (3) Completely fill each subshell before proceeding to the next energy level. Remember the order!!

Orbital Diagrams Practice Problems 1. Fill in the orbital diagrams for: C O Ne Na Si Cl Ar K ___ ___ ___ 4p ___ ___ ___ 4p __ __ __ __ __ 3d __ __ __ __ __ 3d ___ 4s ___ 4s ___ ___ ___ 3p ___ ___ ___ 3p ___ 3s ___ 3s ___ ___ ___ 2p ___ ___ ___ 2p ___ 2s ___ 2s ___ 1s ___ 1s

Orbital Diagrams Practice Problem Answers Fill in the orbital diagrams for: C O ___ ___ ___ 4p ___ ___ ___ 4p __ __ __ __ __ 3d __ __ __ __ __ 3d ___ 4s ___ 4s ___ ___ ___ 3p ___ ___ ___ 3p ___ 3s ___ 3s ___ ___ ___ 2p ___ ___ ___ 2p ___ 2s ___ 2s ___ 1s ___ 1s

Orbital Diagrams Practice Problem Answers Fill in the orbital diagrams for: Ne Na ___ ___ ___ 4p ___ ___ ___ 4p __ __ __ __ __ 3d __ __ __ __ __ 3d ___ 4s ___ 4s ___ ___ ___ 3p ___ ___ ___ 3p ___ 3s ___ 3s ___ ___ ___ 2p ___ ___ ___ 2p ___ 2s ___ 2s ___ 1s ___ 1s

Orbital Diagrams Practice Problem Answers Fill in the orbital diagrams for: Si Cl ___ ___ ___ 4p ___ ___ ___ 4p __ __ __ __ __ 3d __ __ __ __ __ 3d ___ 4s ___ 4s ___ ___ ___ 3p ___ ___ ___ 3p ___ 3s ___ 3s ___ ___ ___ 2p ___ ___ ___ 2p ___ 2s ___ 2s ___ 1s ___ 1s

Orbital Diagrams Group Study Problems Fill in the orbital diagrams and then write the electron configuration (both full and condensed) for: B F Ca P S As Zn Pb ___ ___ ___ 4p __ __ __ __ __ 3d ___ 4s ___ ___ ___ 3p ___ 3s ___ ___ ___ 2p ___ 2s ___ 1s