CHEMISTRY 20 CHEMICAL BONDING VSEPR Theory Morning Assignment
CHEMISTRY 20 CHEMICAL BONDING VSEPR Theory
Morning Assignment Explain how to create a Lewis Dot Diagram for Ne (g) What is a Stereochemical Formula?
VSEPR Vocabulary Valence Shell Electron Pair Repulsion Theory (VSEPR) � So what do you think it is about from the acronym? � It is a model to predict the stereochemistry (shape) of elements & compounds Stereochemistry – study of 3 D configuration of molecules & how this affects reactions
VSEPR Theory Only the valence electrons matter for molecular shape Valence electrons are paired (like we have studied) Bonded pairs & lone pairs are treated equally Valence e- pairs repel each other (electrostatically) Molecular shape (stereochemistry) is
Using VSEPR Theory to predict Stereochemistry Key Concept: All e- pairs repel each other & try to get as far away as possible Bonded Pair: Pair of electrons between the central atom and the peripheral atom Lone Pair: Pair of e- on the central atom with no bonding � Draw picture of NH 3 (g) into notes
Stereochemistry Chart Lewis Bonde Lon d e Pairs Pair s Total Pairs Genera e- pair l arrangeme Formul nt a Stereochemi cal Formula Example s 2 0 2 AX 2 Linear CO 2, CS 2 3 0 3 AX 3 Trigonal Planar BF 3, BH 3 4 0 4 AX 4 Tetrahedral CH 4, Si. H 4 3 1 4 AX 3 E Trigonal Pyramidal NH 3, PCl 3 2 2 4 AX 2 E 2 Angular H 2 O, OCl 2
Steps for Predicting Stereochemical Shape 1. 2. 3. Draw the Lewis Dot Model Count the Bonding and Lone Pairs Reference the chart to determine the shape For ions, put brackets around the whole formula and put the charge in the top right corner.
Assignment Reading � Text Pages 91 – 97 Questions � Text Page 96 #’s 1 – 5 � Text Page 104 #’s 1 -3
- Slides: 8