Ionic Compounds

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Ionic Compounds

• Compounds
• Ionic Properties

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Ionic Compounds

• The ratio of cations to anions is always such
  that an ionic compound has no overall charge

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Ionic compounds Vs Molecules

• Ionic Compounds Do Not Consist of Molecules
• Water is a molecular compound, so individual
  water molecules are each made of two hydrogen
  atoms and one oxygen atom.
• Sodium chloride is an ionic compound, so it is
  made up of many Na and Cl? ions all bonded
  together to form a crystal. There are no NaCl
  molecules

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Ionic Compounds

• Metals and nonmetals tend to form ionic compounds
  and not molecular compounds

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Ionic Bond Strength

• Attractive forces exist between oppositely
  charged ions and involve more than a single
  cation and anion
• Six Na ions surround each Cl? ion and vice
  versa.
• As a result, the attractive force between
  oppositely charged ions is significantly greater
  in a crystal than it would be if the ions existed
  only in pairs.
• Overall, the attractive forces are much stronger
  than the repulsive ones, so ionic bonds are
  strong

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Ionic Properties

• Most ionic compounds have high melting and
  boiling points because of the strong attraction
  between ions
• Like NaCl, most ionic compounds are hard and
  brittle.
• Hard means that the crystal is able to resist a
  large force applied to it.
• Brittle means that when the applied force becomes
  too strong to resist, the crystal develops a
  widespread fracture rather than a small dent.

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Ionic Conductivity

• Ionic solids, such as salts, generally are not
  conductors because the ions cannot move.
• When a salt melts or dissolves, the ions can move
  about and are excellent electrical conductors.

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How to Identify a Compound as Ionic

• All ionic compounds are solid at room
  temperature.
• Tap the substance.
• Ionic compounds do not break apart easily and
  they fracture into tiny crystals.
• Heat the substance.
• Ionic compounds generally have high melting and
  boiling points.
• Use a conductivity device to find if the
  dissolved or melted substance conducts
  electricity.
• Dissolved and molten ionic compounds conduct
  electricity.

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Assignment

• Finish
• SG 33-34
• Ion Worksheet
• Add Ions to periodic Table
• Text pg 175
• 1-11