Lewis Structures/VSEPR Model
Lewis Structures/VSEPR Model Chem 121
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This 5 page Class Notes was uploaded by Pamela Crockett on Monday October 10, 2016. The Class Notes belongs to Chem 121 at University of North Dakota taught by David Pierce in Fall 2016. Since its upload, it has received 258 views.
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Date Created: 10/10/16
Ionic Bonds Ionic bonds form by complete transfer of one or more electrons from one atom to another A monatomic ion is only one atom with charge A polyatomic ion is a group of atoms with charge Naming compounds from formulas… Cation – monatomic (naming rule: element name – Roman “stock” number) Polyatomic (Ammonium: NH4+) Anions – monatomic Writing Lewis Structures: 1. Write skeletal structures 2. Count total # of valence electrons (# pairs) Electron-dot (Octet Rule) Structures: What is bonded to what in polyatomics? Central atom has lowest electronegativity and arrangement should be symmetrical Covalent Bonds and Molecular Structure VSEPR Model: easiest way to predict structCharge clouds move to positions that Valence MAXIMIZE distances Shell: electron dot structures Electron Pair Repulsion: lone and bonding pairs repel each other VSEPR: 5 lowest repulsion geometry’s 1. Linear – 180 degrees 2. Trigonal planar – 120 degrees 3. Tetrahedral – 109.5 degrees 4. Trigonal bipyramidal – 90/120 degrees 5. Octahedral – 90/90 degrees Lecture Notes - 10/3/16 Ionic Compounds: electrons transferred between atoms Molecular Compounds: electrons shared between atoms Main group atoms reach “octet” to bond!!! Telling the difference between Ionic + Covalent bonds…... Compounds show different behavior o Properties (formula mass, physical appearance, type of bond, melting point, boiling point) Gauge sharing with electronegativity o Difference: > or = to 2/Bond Type: Ionic > 0 and <2/Bond Type: Polar Covalent Naming Compounds from Formulas Binary Naming Rule: prefix + element name; prefix + element name + ide First element – no need for “mono” Examples: PCl3 = Phosphorous Trichloride N2O3 = Dinitrogen Trioxide