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Chemical Bonding & Molecular Structure

 

I. Chemical Bonding

A. Bond Formation

1.      Electronegativity

2.      Bond Character

3.      Ionic Bonds

4.      Covalent Bonds

5.      Metallic Bonds

6.      Polyatomic Ions

B. Particle Sizes

1.      Ionic Radii

2.      Covalent Radii

3.      Van der Waals Radii

 

II. Molecular Structure

A. Bonds in Space

1.      Electron Distribution

2.      Electron Pair Repulsion

B. Hybrid Orbitals

1.      Sigma & Pi Bonds

2.      Multiple Bond Molecular Shapes

 

III. Polar Molecules

A. Molecular Attractions

1.      Polarity

2.      Weak Forces

B. Coordination Chemistry

1.      Ligand and Complex Ions

2.      Coordination Compounds

 

 

 

 

Bonds between Hydrogen and Halogens

Bond

Bond Strength

(kJ/mol)

Electronegativity

Difference

H F

568.1

1.90

H Cl

431.951

0.63

H Br

366.25

1.54

H I

298.32

0.01

 

 

 

Character of Bonds

Electronegativity

Difference

0

0.65

0.94

1.19

1.43

1.67

1.91

2.19

2.54

3.03

Percent Ionic Character (%)

0

10

20

30

40

50

60

70

80

90

Percent Covalent

Character (%)

100

90

80

70

60

50

40

30

20

10

 

 

 

Chemical Bond Summary

Bond Type

Generally Formed

Between

Bond Formed by

Properties of Bond Type

Examples

Covalent

Atoms of nonmetallic elements of similar electronegativity

Sharing of electron pairs

Stable nonionizing molecules not conductors of electricity

OF2, C2H6, SiC, ASCl3,

GeCl4, C, Si

Ionic

Atoms of metallic and nonmetallic elements of widely different electronegativities

Electrostatic attraction between ions resulting from transfer of electrons

Charged ions in gas, liquid, and solid. Solid is electrically nonconducting. Gas and liquid are conductors. High melting points.

NaCl, K2O, BaS, LiH, CdF2, BaBr2, ErCl3, CdO, Ca3N2

Metallic

Atoms of metallic elements

Delocalized electron (mobile electron) cloud around atoms of low electronegativity

Electrical conductors in all phases, luster, very high melting points.

Na, Au, Cu, Zn, Ac, Be, Gd, Fe

 

 

 

Weak Forces Summary

 

 

van der Waals forces

Type of Force

Hydrogen bonds

Dispersion forces

Dipole Interactions

Substances

Exhibiting

Force

Very polar polar covalent bond

Nonpolar

molecules

Polar covalent

molecules

Source of

The force

Hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared pair of another electronegative atom.

Weak electrical fluctuations which destroy spherical symmetry of electronic fields around atoms

Electric attraction between dipoles resulting from polar bonds

 

Hydrogen bonds > Dipole Interactions > Dispersion forces

 

Strongest > Weakest