Molecular Molecular ShapeShape

Section 9.4Section 9.4

ChemistryChemistry

ObjectivesObjectives• Discuss the VSEPR bonding theory• Predict the shape of and the bond

angles in a molecule• Define hybridization

The Shape of MoleculesThe Shape of Molecules• The shape of molecules determines

reaction ability• The model we use is the VSEPR

model– Valence Shell Electron Pair Repulsion

VSEPR ModelVSEPR Model• Minimizes the repulsion of shared

and unshared pairs of electrons around the central atom

• 7 key shapes you will need to be able to draw and identify

Linear Molecular ShapeLinear Molecular Shape

• Example: BeCl2• Total Pairs of Electrons: 2• Shared Pairs of Electrons: 2• Lone Pairs: 0• Bond Angle: 180°• Hybrid Orbitals: sp

Trigonal PlanarTrigonal Planar

• Example: AlCl3• Total Pairs of Electrons: 3• Shared Pairs of Electrons: 3• Lone Pairs of Electrons: 0• Bond Angle: 120°• Hybrid Orbitals: sp²

TetrahedralTetrahedral

• Example: CH4

• Total Pairs of Electrons: 4• Shared Pairs of Electrons: 4• Lone Pairs of Electrons: 0• Bond Angle: 109.5°• Hybrid Orbitals: sp³

Trigonal PyramidalTrigonal Pyramidal

• Example: PH3

• Total Pairs of Electrons: 4• Shared Pairs of Electrons: 3• Lone Pairs of Electrons: 1• Bond Angle: 107.3°• Hybrid Orbitals: sp³

BentBent

• Example: H2O

• Total Pairs of Electrons: 4• Shared Pairs of Electrons: 2• Lone Pairs of Electrons: 2• Bond Angle: 104.5°• Hybrid Orbitals: sp³

Trigonal BipyramidalTrigonal Bipyramidal

• Example: NbBr5

• Total Pairs of Electrons: 5• Shared Pairs of Electrons: 5• Lone Pairs of Electrons:0• Bond Angle: 90°, 120°• Hybrid Orbitals: sp³d

OctahedralOctahedral

• Example: SF6

• Total Pairs of Electrons: 6• Shared Pairs of Electrons: 6• Lone Pairs of Electrons: 0• Bond Angle: 90°• Hybrid Orbitals: sp³d²

HybridizationHybridization• Hybridization: A process in which

atomic orbitals are mixed to form new, identical hybrid orbitals– Carbon is the most common – The number of hybrid orbitals = the

number of total pairs of electrons

HomeworkHomework• 54-59 on page 262