Page 1:

• Molecular shapes can be predicted using the VSEPR theory

• Lewis structures are two-dimensional representations of molecules

• Molecules are actually three-dimensional

• The shape of a molecule determines its physical and chemical properties

Page 2:

• The structures shown in the left-hand column of Model 1 are Lewis Structures

• A solid line between two element symbols represents a covalent bond

• The solid lines are made up of electrons

• A pair of dots represents a lone pair of electrons

• The dots are also made up of electrons

• "Domain" means an area within something or someone's control

• Molecules with four electron domains: H2O, NH3, CH4

• Molecules with two electron domains: CO2, BeF2

• Molecule with three electron domains: H2CO

• When determining the number of electron domains, count bonds and lone pairs on the center atom

Page 3:

• A bonding electron domain is a bond on the central atom

• A nonbonding electron domain is a lone pair on the central atom

• Pairs of electrons repel each other

• Two bonds on the same atom try to get as far from each other as possible

• A lone pair of electrons and a bonded pair of electrons push away from each other

• VSEPR theory is based on the premise that electrons around a central atom repel each other

• Valence shell electrons are the most critical for determining molecular shape

• Electrons around the central atom repel each other in VSEPR theory

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• None of the molecular shapes in Model 1 have 90° bond angles

• The bond angles in three-dimensional molecules are generally larger than those in Lewis structures

• Three-dimensional molecules have larger angles because electrons have an additional dimension to move away in

• Molecules with four electron domains: H2O, NH3, CH4

• As the number of lone pairs on the central atom increases, the bond angle decreases

Page 5:

• Lewis structure for H2S: H - S - H

• 3-D drawing: Bent

• Bond angle: 104.5°

• Lewis structure for PH3: P - H

• 3-D drawing: Pyramidal

• Bond angle: 107°

• Lewis structure for CCl4: C - Cl

• 3-D drawing: Tetrahedral

• Bond angle: 109.5°

• Lewis structure for CS2: C = S

• 3-D drawing: Linear

• Bond angle: 180°

Page 6:

• Lewis structure for ozone (O3): O = O - O

• Ozone has a bent shape instead of a linear shape

• Ozone's bond angle is larger than that of water (H2O) because it has three electron