Chemistry- structure and properties

Chemistry- structure and properties

• Giant iconic structures
• An ionic compound consists of a giant structure of ions arranged in a lattice. The attractive electrostatic forces between the oppositely charged ions act in all directions and are very strong. This holds the ions in the lattice together very tightly.
• It takes a lot of energy to break up a giant ionic lattice. There are lots of strong ionic bonds to break. To separate the ions we have to overcome all those electrostatic forces of attraction. This means that ionic compounds to have high melting points and boiling points.
• Once we have supplied enough energy to separate the ions from the lattice, they are free to move around, that's when the ionic solid melts and becomes a liquid. Therefore they can carry their electrical charge through the molten liquid. A solid ionic compound cannot conduct electricity, that's because its ions are held in a fixed position in the lattice. They cannot move around. They can only vibrate 'on the spot' when solid.
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• Caption: The attractive forces between the oppositely charged ions in an ionic compound are very strong. The regular arrangement of ions in the giant lattice enables ionic compounds to form crystals.

Giant ionic structures

• Many ionic compounds will dissolve in water. When we dissolve an ionic compound in water, the lattice is slit up by the water molecules. Then the ions are free to move around in the solution formed. Just as molten ionic compounds will conduct electricity, solutions of ionic compounds will also conduct electricity. The ions are able to move to an oppositely charged electrode dipped in the solution.
• Ionic solid- Ions are fixed in a lattice. They vibrate but cannot move around- it does not conduct electricity.
• Molten Ionic compound- High temperature provides enough energy to overcome the many strong attractive forces between ions. Ions are free to move around within the molten compound- it does conduct electricity
• Ionic compound in solution- Water molecules separate ions from the lattice. Ions are free to move around within the solution- it does conduct electricity