Chapter 6 Section 5 Part 1: Molecular Geometry VSEPR

Chapter 6 Section 5 Part 1: Molecular Geometry-VSEPR Theory

​Introduction

• ​Properties of molecules depend on the arrangement of the molecules

  • ​Molecular Geometry: The three-dimensional arrangement of Atoms in space

    • ​Chemical Formulas reveal little about a molecule's geometry

    • ​Two methods are used to reveal the shapes

      • ​VSEPR

      • ​Hybridization

​VSEPR

• ​Valence-Shell, Electron Pair Repulsion

  • ​The Repulsion between the sets of valence electrons surrounding an atom forces sets of atoms to be oriented as far apart as possible

    • ​Think of a group of magnets, each one moves until they are balanced

• ​VSPER Shows what type of shape the atoms of a molecule form

​How VSEPR Works

• ​Let's look at the molecule BeF₂

  • ​Remember Beryllium is special and does not follow the octet rule

  • ​According to VSEPR, the shared electron pairs will be as far away from each other as possible

    • ​The only way this can happen is if they are in a straight line

​VSPER Theory and unshared Electron Pairs

• ​Some molecules have unshared electron pairs in their structures

  • ​Ammonia (NH₃₎

  • ​Water (H₂O)

• ​VSEPR Treats these unpaired electrons as though they occupy the space around the central atom, but do not affect how we see the shape

• ​In a generic formula unpaired electrons are represented by the letter E

​A & B = atoms

​E= Loose electron Pairs

​Practice

• ​Use VSPER theory to predict the molecular geometry of boron Trichloride BCl₃

  • Start with electron dot notation of BCl₃

  • ​What Type of Molecule is BCl_3?

    • ​AB₃

      • ​This shape Corresponds to Trigonal Planar

Fill in the Blanks

Use VSEPR Theory to predict the molecular geometry of the molecule HI.

Fill in the Blanks

Use VSEPR Theory to predict the molecular geometry of the molecule CBr₄.

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Use VSEPR Theory to predict the Molecular Geometry of the molecule CH₂Cl₂.

Fill in the Blanks

Use VSEPR theory to predict the molecular geometry of a molecule of CO₂

Fill in the Blanks

Use VSEPR Theory to predict the shape of a Chlorate Ion (ClO₃)

Fill in the Blanks

Use VSEPR Theory to predict the shape of the molecule SeF₆