Ionic Bonding

Resonance Structures

VSEPRBasic Shapes3-D NotationHybridization (Lab)

M olecular G eom etries

Octet Rule Polar M olecules

Lew is Structures Covalent Bonding

T ypes of Bonds

Chemical BondingChemical Bonding

Chemical compoundsChemical compounds

• Chemical bond: attractive force holding two or more atoms together.

• Ionic bond results from the transfer of electrons from a metal to a nonmetal.

• Covalent bond results from sharing electrons between the atoms. Usually found between nonmetals.

• Metallic bond attractive force holding pure metals together.

Chemical Bonds, Lewis Symbols, and the Octet RuleChemical Bonds, Lewis Symbols, and the Octet Rule

Ionic CompoundsIonic Compounds

Ionic Bonds: One Big Greedy Thief Dog!

Covalent BondingCovalent Bonding

Polar Covalent Bonds: Unevenly matched, but willing to share.

Metallic BondingMetallic Bonding

Metallic Bonds: Mellow dogs with plenty of bones to go around.

Covalent BondingCovalent Bonding

Lewis Symbols

Chemical Bonds, Lewis Symbols, and the Octet RuleChemical Bonds, Lewis Symbols, and the Octet Rule

Drawing Lewis StructuresDrawing Lewis Structures

Follow Step by Step Method

1. Total all valence electrons. [Consider Charge]

2. Write symbols for the atoms and guess skeleton structure [ define a central atom ].

3. Place a pair of electrons in each bond.

4. Complete octets of surrounding atoms. [ H = 2 only ]

5. Place leftover electrons in pairs on the central atom.

6. If there are not enough electrons to give the central atom an octet, look for multiple bonds by transferring electrons until each atom has eight electrons around it.

Exceptions to the Octet RuleExceptions to the Octet Rule

Central Atoms Having Less than an Octet• Relatively rare.• Molecules with less than an octet are typical for

compounds of Groups 1A, 2A, and 3A.

• Most typical example is BF3, with only 6

• Formal charges indicate that the Lewis structure with an incomplete octet is more important than the ones with double bonds.

• There are five fundamental geometries for molecular shape:

Molecular Shapes: VSEPRMolecular Shapes: VSEPR

Figure 9.3

HyperChem

e-pairs Notation Name of VSEPR shape Examples

2 AX2 Linear HgCl2 , ZnI2 , CS2 , CO2

3 AX3 Trigonal planar BF3 , GaI3

AX2E Non-linear (Bent) SO2 , SnCl2

4 AX4 Tetrahedral CCl4 , CH4 , BF4-

AX3E (Trigonal) Pyramidal NH3 , OH3-

AX2E2 Non-Linear (Bent) H2O , SeCl2

5 AX5 Trigonal bipyramidal PCl5 , PF5

AX4E Distorted tetrahedral

(see-sawed)

TeCl4 , SF4

AX3E2 T-Shaped ClF3 , BrF3

AX2E3 Linear I3- , ICl2

-

6 AX6 Octahedral SF6 , PF6-

AX5E Square Pyramidal IF5 , BrF5

AX4E2 Square Planar ICl4- , BrF4

-

Timberlake LecturePLUS 27

Timberlake LecturePLUS 28

MolecularGeometries

and Bonding

Polarity

SO

O

Just as electrons push away from each other, so do molecules

HBrHBr is a polar molecule: dipole-dipole forces. There are also dispersion forces between HBr molecules.

CH4

CH4 is nonpolar: London dispersion forces, caused by “temporary dipoles”.

SO2

SO2 is a polar molecule: dipole-dipole forces. There are also dispersion forces between SO2 molecules.

SO

O

What type(s) of intermolecular forces exist between each of the following molecules?

HBrHBr is a polar molecule: dipole-dipole forces. There are also dispersion forces between HBr molecules.

CH4

CH4 is nonpolar: dispersion forces.

SO2

SO2 is a polar molecule: dipole-dipole forces. There are also dispersion forces between SO2 molecules.

Intermolecular Forces

Intermolecular Forces

Hydrogen Bond

The hydrogen bond is a special dipole-dipole interaction between they hydrogen atom in a polar N-H, O-H, or F-H bond and an electronegative O, N, or F atom.

A H…B A H…Aor

A & B are N, O, or F

Intermolecular Forces

Dispersion Forces

Attractive forces that arise as a result of temporary dipoles induced in atoms or molecules

ion-induced dipole interaction

dipole-induced dipole interaction