Chemical Bonding

1
I. Introduction toBonding

• Chemical Bonding

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A. Vocabulary

• Chemical Bond
• attractive force between atoms or ions that binds
  them together as a unit
• bonds form in order to
• decrease potential energy (PE)
• increase stability

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A. Vocabulary
CHEMICAL FORMULA
IONIC
COVALENT
Molecular Formula
Formula Unit
CO2
NaCl
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A. Vocabulary
COMPOUND
more than 2 elements
2 elements
Ternary Compound
Binary Compound
NaNO3
NaCl
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A. Vocabulary
ION
2 or more atoms
1 atom
Polyatomic Ion
Monatomic Ion
NO3-
Na
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B. Types of Bonds
Ionic Covalent
Type of Elements Metal Nonmetal Nonmetal Nonmetal
Smallest Unit is called Formula Unit Molecule
Type of Bonding Crystal Lattice True Molecules
Valence Electrons are Transferred Shared
Physical State at room temperature Solid Liquid or Gas
Melting Point High Low
Hardness Hard Soft
Conducts Electricity Yes No
Examples NaCl H2O
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B. Types of Bonds
Ionic Bonding - Crystal Lattice
RETURN
8
B. Types of Bonds
Covalent Bonding - True Molecules
Diatomic Molecule
RETURN
9
B. Types of Bonds
METALLIC
e- are delocalized among metal atoms
Bond Formation
Type of Structure
electron sea
Physical State
solid
Melting Point
very high
Solubility in Water
no
yes (any form)
Electrical Conductivity
malleable, ductile, lustrous
Other Properties
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B. Types of Bonds
Metallic Bonding - Electron Sea
RETURN
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C. Lewis Structures

• Electron Dot Diagrams
• show valence e- as dots
• distribute dots like arrows in an orbital
  diagram
• 4 sides 1 s-orbital, 3 p-orbitals
• EX oxygen

O
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C. Lewis Structures

• Octet Rule
• Most atoms form bonds in order to obtain 8
  valence e-
• Full energy level stability Noble Gases

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C. Lewis Structures

• Covalent show sharing of e-
• Ionic show transfer of e-

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C. Lewis Structures

• Covalent show sharing of e-
• Ionic show transfer of e-

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D. Bond Polarity

• Most bonds are a blend of ionic and covalent
  characteristics.
• Difference in electronegativity determines bond
  type.

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D. Bond Polarity

• Electronegativity Trend
• Increases up and to the right.

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D. Bond Polarity

• Electronegativity
• Attraction an atom has for a shared pair of
  electrons.
• higher e-neg atom ? ?-
• lower e-neg atom? ?

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D. Bond Polarity

• Nonpolar Covalent Bond
• e- are shared equally
• symmetrical e- density
• usually identical atoms

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D. Bond Polarity

• Polar Covalent Bond
• e- are shared unequally
• asymmetrical e- density
• results in partial charges (dipole)

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D. Bond Polarity

• Examples
• Cl2
• HCl
• NaCl

3.0-3.00.0 Nonpolar 3.0-2.10.9 Polar 3.0-0.92.1
Ionic
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D. Bond Polarity w/ Lewis Structures

• Nonpolar Covalent - no charges
• Polar Covalent - partial charges