Chemical Bonding

1
Chemical Bonding

• Ionic Compounds

2
Ionic Compound

• Composed of a metal (cation) and nonmetal (anion)
• Ionic bond oppositely charged ions attract
• Electrically neutral () (-)

Properties

• 1. ionic compounds form crystals
• 2. high melting and boiling points
• 3. hard and brittle
• 4. conduct electricity when dissolved in water or
  melted

3
Steps to Ionic Bonding

• Copy the problem
• Draw the Lewis Structure for ea. element used in
  bonding
• CATION RED
• ANION BLUE/GREENISH
• Show donated e- with an arrow
• Show New ions charges
• Put a BOX around the Formula

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Ionic Bonding
1
-1
1. Sodium and Chlorine
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donates e-
Na
Cl
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Cl
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• Na

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NaCl
1
-2
2. Potassium and Oxygen
Does O have 8?
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donates e-
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O
K
-2
K
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O

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donates e-
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K
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K
K2O
5
AlBr3
3
-1
3. Aluminum and Bromine
-
Does Al have more electrons?
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Br
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Br
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• Al

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-
Al3
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Br
Br

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-
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Br
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Br
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2
-3
4. Magnesium and Nitrogen
Mg2
-3
Does N have 8 yet?
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Mg
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N
N
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Mg2
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-3
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What about Mgs other e-?
N
Mg
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Mg2
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N
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Mg
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Mg3N2
Does N have 8 yet?
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Important differences between covalent and ionic
compounds
Characteristic Covalent compound Molecular compound Ionic compound
Representative unit Molecule (atoms sharing electrons) Formula unit (balance of oppositely charged ions)
Type of elements Nonmetallic Metallic combined with nonmetallic
Melting Boiling point Low High
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Bonding in Metals

• Metallic bonds the attraction between positive
  ions and surrounding mobile electrons

Sea of Electrons
Metal cations

• Good conductors of electrical current, ductile
  (wires), malleable (forced into shapes)