Geometry ofGeometry of MMoleculesolecules

VSEPR TheoryVSEPR Theory

Valence Shell Electron Pair Valence Shell Electron Pair Repulsion TheoryRepulsion Theory (VSEPR)(VSEPR)

The geometry of the molecule at The geometry of the molecule at any given central atom is any given central atom is determined by the repulsions of determined by the repulsions of both bonding and nonbonding (lone both bonding and nonbonding (lone pair) electrons in the valence shell.pair) electrons in the valence shell.

HybridizationHybridization

When atoms join When atoms join to form molecules, to form molecules, the electron the electron density regions density regions change.change.

HybridizationHybridization

The process of mixing different The process of mixing different orbitals of the same atom to form a orbitals of the same atom to form a new set of equivalent orbitals is new set of equivalent orbitals is termed termed hybridization.hybridization.

The shape of the molecule The shape of the molecule depends of the number of electron depends of the number of electron pairs on the central atom and the pairs on the central atom and the orientation of the hybrid orbitals.orientation of the hybrid orbitals.

VSEPRVSEPR

Shapes expected for different Shapes expected for different numbers of electron pairsnumbers of electron pairs

Two Pairs of ElectronsTwo Pairs of Electrons

BeHBeH22

Linear moleculeLinear molecule

There are two pairs of electrons on the There are two pairs of electrons on the central atom, beryllium.central atom, beryllium.

sp hybridsp hybrid

Linear MoleculeLinear Molecule

Three Pairs of ElectronsThree Pairs of Electrons

BClBCl33

Planar triangular, 120Planar triangular, 120oo

spsp22 hybrid hybrid

There are three pairs of electrons on the central atom, boron.

Planar Triangular Planar Triangular MoleculeMolecule

Hybrid OrbitalsHybrid Orbitals

Four Pairs of ElectronsFour Pairs of Electrons

CHCH44

Tetrahedral, 109.5Tetrahedral, 109.5oo

There are four pairs There are four pairs of electrons on the of electrons on the central atom, carbon.central atom, carbon. spsp33 hybrid hybrid

Tetrahedral MoleculeTetrahedral Molecule

Organic CompoundsOrganic Compounds

A huge number of the compounds that A huge number of the compounds that exist on Earth are carbon-containing exist on Earth are carbon-containing compounds that have the tetrahedral compounds that have the tetrahedral shape around each carbon atom.shape around each carbon atom.

Four Pairs of ElectronsFour Pairs of Electrons

Molecular shapes with four electron pairs around the central atom.

Five Pairs of ElectronsFive Pairs of Electrons

PClPCl55

Trigonal bipyramidalTrigonal bipyramidal

9090oo and 120 and 120oo

spsp33d hybridd hybrid

spsp33d and spd and sp33dd22 Hybrid OrbitalsHybrid Orbitals

Six Pairs of ElectronsSix Pairs of Electrons

SFSF66

Octahedral, 90Octahedral, 90oo

spsp33dd22 hybrid hybrid

VSEPR TheoryVSEPR Theory

Molecular geometry affects the Molecular geometry affects the characteristics of all compounds.characteristics of all compounds.

Learn more with the Learn more with the

VESPR Molecular Model KitVESPR Molecular Model Kit