1ACh9 - Ch 9 Molecular Geometry and Bonding Theories...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch. 9 Molecular Geometry and Bonding Theories Fundamental Properties of Models Models are human inventions that explain how nature works but do not equal reality Models are often wrong to some degree Models tend to become more complicated as they are updated Models are limited by their assumptions We learn even when the model is shown to be wrong The Localized Electron Bonding Model The Localized Electron (LE) model assumes that a molecule is composed of atoms that are bound together by sharing pairs of electrons using the atomic orbitals of the bound atoms Electron pairs are assumed to be localized on a particular atom or between atoms Electron pairs localized on an atom are lone pairs Electron pairs localized between atoms are bonding pairs . The LE model has 3 parts Description of valence electron arrangement using Lewis structures Prediction of the geometry of the molecule using valence shell electron pair repulsion (VSEPR) model Description of the type of atomic orbitals containing the electrons 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Molecular Structure: The VSEPR Model Molecular Geometry Molecular Structure is the three dimensional arrangement of atoms in a molecule Electronic Geometry Electronic Structure is the three dimensional arrangement of valence orbitals (areas of electron density {Electron Domains}) in a molecule. Electron Domains consist of each nonbonding electron pair and each bond (bonded atom). Valence Shell Electron-Pair Repulsion (VSEPR) Model Valence Shell Electron-Pair Repulsion (VSEPR) Model is a simple but useful method of estimating molecular structure of nonmetals The postulate is that the structure around a given atom is determined by miminizing electron-pair repulsions. VSEPR Model and Multiple Bonds Double bonds count as one electron domain, one area of electron density Triple bonds also count as one electron domain, one area of electron density When resonance structures exist, any one of the resonance structures can be used to predict the molecular structure. Linear Structure A Linear Structure results when there are two areas of electron density around an atom The bond angle is 180 ° Trigonal Planar Structure A Trigonal Planar Structure results when there are three areas of electron density around an atom The bond angle is 120 ° 2
Background image of page 2
Tetrahedral Arrangement Tetrahedral Arrangement results when there are four areas of electron density around an atom The bond angle is a09.5 ° Trigonal pyramid Three bonding pairs and a lone pair results in a Trigonal pyramid configuration Bent or Angled Two bonding pairs and two lone pairs results in a bent or angled configuration Trigonal bipyramid Trigonal bipyramid arrangement results when there are five areas of electron density around an atom Octahedral Structure Octahedral Structure arrangement results when there are six areas of electron density around an atom Square Planar Structure Four bonding pairs and two lone pairs results in a Square Planar Structure 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Total e- domains Electron Geometry Hybrid
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2008 for the course CHEM 1 taught by Professor Evans during the Fall '06 term at UC Irvine.

Page1 / 12

1ACh9 - Ch 9 Molecular Geometry and Bonding Theories...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online