Chemical Bonding

1
Chemical Bonding

• combining of atoms of elements to form new
  substances
• ability to bond depends on valence e-
• bonding occurs if the bond will give both atoms
  stability (8 valance e- or 2 valence e-)
• atoms will gain/lose or share e-

2
IONIC BONDING

• involves a transfer of electrons
• by gaining/losing e-, atoms become or
• formed between a metal and a nonmetal

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IONIC BONDING
4
COVALENT BONDING

• bonding that shares e-
• occurs between nonmetals
• neither want to lose e-, both want to gain e- to
  be stable

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Lewis Dot/Electron Dot Notation

• Na
• B
• C
• O
• F

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Ionic Bonding

• NaCl
• KF
• CsI

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Covalent Bonding

• H2
• F2
• O2
• N2

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POLAR COVALENT BOND

1. the electrons shared by the atoms spend a greater
   amount of time closer to one particular atom
2. This creates a partial negative end and a partial
   positive end

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Electronegativity Bond Type
Electronegativity Bond Type Example
0.0-0.49 Nonpolar covalent H-H (0.0)
0.5-1.69 Polar covalent H-Cl (0.9)
gt1.7 Ionic Na-Cl (2.1)
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METALLIC BOND

• formed between 2 or more metal atoms
• metals give up e-, no atoms wants to take the e-
  so they end up forming a common e- cloud

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METALLIC BOND

• This common electron cloud is what gives metals
  the properties of
• malleabilitymakes into sheets
• conductivity
• high melting point
• strong bond
• ductilemakes into thin wire
• metallic luster

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NUMBER OF BONDS BETWEEN ATOMS

• Single bonds one pair of electrons longest
  bond length weakest bond
• O H O
• Double bonds two pairs of electrons
• OCO
• Triple bonds three pairs of electrons shortest
  bond length strongest bond

N N
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INTERMOLECULAR FORCES

• London Dispersion Forces (Van der Waals Forces)
• 1. weakest of all intermolecular forces
• 2. the attractive or repulsive force between
  molecules (or between parts of the same
  molecule)
• Dipole-Dipole Interactions
• 1. between polar molecules
• Hydrogen Bonds
• 1. strongest of all intermolecular forces
• 2. hydrogen bonded to a very electronegative
  atom (O,N,F)
• H F

N N
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VSEPR

• Valence Shell Electron-Pair Repulsion
• A. predicts the shape of individual molecules
  based upon the extent of electron-pair
  electrostatic repulsion
• B. Double bonds count as one pair of electrons

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Bond Angle atoms e- pairs unshared e- pairs Example
Linear 180 3 2 0 BeCl2 CO2
Bent 104.5? 3 4 2 H2O
Trigonal Pyrimidal 107 4 4 1 NH3
Tetrahedral 109.5? 5 4 0 CH4
Trigonal Planar 120 4 3 0 BF3
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SO2
Bent 104.5
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CO2
Linear 180
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CF2Cl2
Tetrahedral 109.5
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NH4
Tetrahedral 109.5
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O3
Bent 104.5
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BeCl2
Linear 180
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H2O
Bent 104.5
23
SO42-
Tetrahedral 109.5
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NH3
Trigonal Pyrimidal 107
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CH4
Tetrahedral 109.5
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BCl3
Trigonal Planar 120