Chem 1211 1st Edition Lecture 22Outline of Last Lecture I. Lewis Dot StructuresOutline of Current Lecture I. Octet RuleII. GeometryIII. ElectronegativityCurrent LectureI. Octet Rulea. ConcepTest: How many lone pair electrons on the central atom, single bonds, double bonds, and triple bonds, respectively, appear in the Lewis structure of PF6-?i. 0, 3, 3, 0ii. 0, 6, 0, 0iii. 1, 3, 3, 0iv. 1, 6, 0, 0 v. 2, 6, 0, 01. ANSWER: 0, 6, 0, 0 2. REASONING: Phosphorus forms a single bond with each of the 6 fluorinesII. Geometrya. What is the geometry for AlCl3?i. Octahedralii. Trigonal bipyramidaliii. Tetrahedraliv. Trigonal planarv. Linear 1. ANSWER: Trigonal planarThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Electron pair geometry and molecular geometryc. VSEPR- valence shell electron pair repulsioni. Pairs of e- occupy space1. Bonding and nonbondingii. Molecular Geometry Shapes:1. Linear- one main element and 2 others (180 degrees)2. Trigonal planar- one main element and 3 others (flat 120 degrees)3. Tetrahedral- one main element and 4 others4. Trigonal bipyramidal- one main element and 5 others (120 degrees and 90 degrees)5. Octahedral- one main element and 6 others (60 degrees)iii. ConcepTest: What are the electron-pair and molecular geometries for PCl3?1. Answer: tetrahedron, trigonal pyramid2. Reasoning: Start with the Lewis structure of PCl3. Phosphorus has 5 electrons and each of the chorines has 7, so phosphorus will make 3 single bonds with each of the chlorines. iv. Electron Pair Geometry1. 4 pairs of electronsa. Tetrahedral- 4 bond pairs, no lone pairs (ex. CH4)b. Trigonal pyramidal- 3 bond pairs, 1 lone pair (ex. NH3)c. Bent- 2 bond pairs, 2 lone pairs (H2O) 2. 5 pairs of electronsa. Trigonal bipyramidal- 5 bond pairs, no lone pairsb. Seesaw- 4 bond pairs, 1 lone pairc. T-shaped- 3 bond pairs, 2 lone pairsd. Linear- 2 bond pairs, 3 lone pairs3. 6 electron pairsa. Octahedral- 6 bond pairs, 0 lone pairsb. Square pyramidal- 5 bond pairs, 1 lone pairc. Square planar- 4 bond pairs, 2 lone pairs d. Share e- between atom making moleculesi. Simplest model: Lewisii. Shapes, geometriesiii. Bond, moleclular propertiesIII. Electronegativitya. Electronegativity increases as you move from left to right and as you move from bottom to top across the periodic tableb. ConcepTest: Which pair has the higher electronegativity listed FIRST?i. B, Cii. C, Niii. N, Oiv. Cl, S1. ANSWER: Cl, S2. Reasoning: Follow periodic table trendsc. The electronegativity of A and B i. If it is less than .5, it is a covalent bond (equal sharing)ii. If it is between .7 and 1.8, it is a polar covalentiii. If it is greater than 2.0, it is an ionic
View Full Document
Unlocking...