Properties of ionic compounds
Ionic compounds have a relatively high melting temperature. Even the common table salt (NaCl) has a melting temperature around 700 degrees Celsius.

The crystal is held together very strongly by directional, electrostatic forces of attraction, as positive and negative ions attract each other. The ions simply vibrate in the solid state and flow freely when heat is applied to melt the crystal. As seen on the right, the ions are packed tightly in the crystal by electrostatic forces and each ion is surrounded by 6 (as in the case of NaCl) other ions of opposite charge.
In the molten state, free moving ions can conduct an electric current. While in the solid state the fixed position of the ions makes it impossible to conduct an electric current.

An ionic compound can conduct electricity in the molten state. Free moving charges will complete the circuit and electron flow will take place. Click to see an animation of he procedure. Scan the image for more information.

Click to see an animation of the electrolysis of molten sodium chloride.

The fact that directional, electrostatic forces act in very specific directions in the crystal lattice makes ionic compounds very brittle. When a force (hammer) is applied to the crystal the ions, which are aligned with opposite charged ions, are pushed out of alignment and now find themselves next to similar charged ions. Directional forces of repulsion result that results int he shattering of the crystal.

Click to see an animation

Most ionic compounds are soluble in water. In solution the charges are pulled apart by the disruptive nature of the water molecules. Water molecules, with their tiny charges, move amongst the ions and destroy the electrostatic attraction between them. Water molecules surround the ions and move about the solution freely. When in solution ionic compounds can conduct an electric current, for there are free moving ions.

Click to see an animation of the dissolving of ionic compounds. Notice how the water molecules orient themselves around the different ions.

 Dissolving of ionic compounds.

Exercises

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Negative chlorine ions are attracted to the anode and form chlorine gas. Positive sodium ions are attracted to the cathode and form sodium metal. Power source Water molecules orient themselves to expose their negative end to the positive ion.Water molecules orient themselves to expose their negative end to the positive ion. Water molecules orient themselves to expose their negative end to the positive ion.Water molecules orient themselves to expose their negative end to the positive ion. Water molecules orient themselves to expose their negative end to the positive ion. Water molecules orient themselves to expose their negative end to the positive ion.Water molecules orient themselves to expose their negative end to the positive ion. The water molecules orient themselves to expose their positive end to the negative ion. The water molecules orient themselves to expose their positive end to the negative ion. The water molecules orient themselves to expose their positive end to the negative ion.