Characteristics of Ionically Bonded Substances

A substance that is ionically bonded is called an ionic compound. All ionic compounds share certain properties, such as high melting and boiling points. This is because the strong bonds between ions in an ionic compound prevent the ions from moving much without a large amount of energy. Because of the aforementioned high boiling point, ionic compounds are almost never found as a gas at room temperature. Ionic compounds contain charged particles, so they are able to conduct electricity. However, because ionic solids are in fixed locations, they are usually not good conductors of electricity. When ions can move, as in a liquid, salts are good conductors of electricity. If a solid salt is dissolved in water, it would then be a good conductor of electricity because its ions are no longer tightly packed together and are now able to move. There are some exceptions, though. There are a few ionic compounds who have an unusually open lattice structure, so ions can move past each other. These solids are good conductors of electricity. Most ionic compounds are hard and brittle. These qualities can be associated with the layered pattern of the cations and anions in salts. When a force is applied to the salt and a layer shifts, the cations of one layer are lined up with the cations of the next layer (the same happens with the anions). This causes them to repel each other and the layers to split apart. That is why all salts break along what is called a cleavage plane, or a line extending throughout the crystal. The ions in the salt form reoccurring patterns because each ion is held in place by attractive forces, which are stronger than the repulsive ones. These repeating units form the crystal lattice, and are the reason for the crystal shape found in most salts. The smallest repeating unit found in the crystal is called a unit cell. The shape of the crystal structure depends on the ratio of each element in the compound.