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Chemistry 8.3 8.3.

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Bonding Theories 8.3 This car is being painted by a process called electrostatic spray painting. The negatively charged droplets are attracted to the auto body. You will learn how attractive and repulsive forces influence the shapes of molecules.
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Page 1: Chemistry 8.3 8.3.

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Chemistry 8.3

8.3

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© Copyright Pearson Prentice Hall

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Bonding Theories

This car is being painted by a process called electrostatic spray painting. The negatively charged droplets are attracted to the auto body. You will learn how attractive and repulsive forces influence the shapes of molecules.

8.3

Page 3: Chemistry 8.3 8.3.

© Copyright Pearson Prentice Hall

Bonding Theories >

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8.3 Molecular Orbitals

Molecular Orbitals

How are atomic and molecular orbitals related?

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Bonding Theories >8.3 Molecular Orbitals

When two atoms combine, the molecular orbital model assumes that their atomic orbitals overlap to produce molecular orbitals, or orbitals that apply to the entire molecule.

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Bonding Theories >8.3 Molecular Orbitals

Just as an atomic orbital belongs to a particular atom, a molecular orbital belongs to a molecule as a whole.

A molecular orbital that can be occupied by two electrons of a covalent bond is called a bonding orbital.

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Bonding Theories >8.3 Molecular Orbitals

Sigma Bonds

When two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting two atomic nuclei, a sigma bond is formed.

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Bonding Theories >8.3 Molecular Orbitals

A Sigma Bond

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Bonding Theories >8.3 Molecular Orbitals

When two fluorine atoms combine, the p orbitals overlap to produce a bonding molecular orbital. The F—F bond is a sigma bond.

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Bonding Theories >8.3 Molecular Orbitals

Pi Bonds

In a pi bond (symbolized by the Greek letter ), the bonding electrons are most likely to be found in sausage-shaped regions above and below the bond axis of the bonded atoms.

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© Copyright Pearson Prentice Hall

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Bonding Theories >8.3 Molecular Orbitals

Pi-bonding Molecular Orbital

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Bonding Theories >

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8.3 VSEPR Theory

VSEPR Theory

How does VSEPR theory help predict the shapes of molecules?

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Bonding Theories >8.3 VSEPR Theory

The hydrogens in a methane molecule are at the four corners of a geometric solid. All of the H—C—H angles are 109.5°, the tetrahedral angle.

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Bonding Theories >8.3 VSEPR Theory

The valence-shell electron-pair repulsion theory, or VSEPR theory, explains the three-dimensional shape of methane.

Page 14: Chemistry 8.3 8.3.

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Bonding Theories >8.3 VSEPR Theory

According to VSEPR theory, the repulsion between electron pairs causes molecular shapes to adjust so that the valence-electron pairs stay as far apart as possible.

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Bonding Theories >8.3 VSEPR Theory

The measured H—N—H bond angle is only 107°.

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Bonding Theories >8.3 VSEPR Theory

The measured bond angle in water is about 105°.

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Bonding Theories >8.3 VSEPR Theory

The carbon dioxide molecule is linear.

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Bonding Theories >8.3 VSEPR Theory

Nine Possible Molecular Shapes

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© Copyright Pearson Prentice Hall

Bonding Theories >

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8.3 Hybrid Orbitals

Hybrid Orbitals

In what ways is orbital hybridization useful in describing molecules?

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Bonding Theories > Hybrid Orbitals

Orbital hybridization provides information about both molecular bonding and molecular shape.

In hybridization, several atomic orbitals mix to form the same total number of equivalent hybrid orbitals.

8.3

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© Copyright Pearson Prentice Hall

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Bonding Theories >8.3 Hybrid Orbitals

Hybridization Involving Single Bonds

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Bonding Theories >8.3 Hybrid Orbitals

Hybridization Involving Double Bonds

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Bonding Theories >8.3 Hybrid Orbitals

Hybridization Involving Triple Bonds

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© Copyright Pearson Prentice Hall

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Bonding Theories > Hybrid Orbitals

Simulation 7 Compare sp, sp2, and sp3 hybrid orbitals.

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© Copyright Pearson Prentice Hall

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Section Quiz

-or-Continue to: Launch:

Assess students’ understanding of the concepts in Section 8.3.

8.3 Section Quiz.

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8.3 Section Quiz.

1. A molecular orbital belongs to a

a. specific atom.

b. molecule as a whole.

c. specific pair of atoms.

d. central atom.

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© Copyright Pearson Prentice Hall

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8.3 Section Quiz.

2. VSEPR theory enables prediction of 3-dimensional molecular shape because the valence electron pairs

a. are attracted to each other.

b. form molecules with only four possible shapes.

c. stay as far apart as possible.

d. always form tetrahedral shapes.

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© Copyright Pearson Prentice Hall

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3. Orbital hybridization provides information about

a. both molecular bonding and molecular shape.

b. both molecular bonding and bond energy.

c. neither molecular bonding nor molecular shape.

d. neither molecular bonding nor bond energy.

8.3 Section Quiz.

Page 29: Chemistry 8.3 8.3.

END OF SHOW


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