Ionic and Molecular Compounds
Ionic compounds are pure substances formed when two or more ions are held next to each other by electrical attraction. Also, it is formed when a metal is in the presence of a non-metal. One of the ions has a positive charge, or cation, and the other has a negative charge, or anion. Cations are usually metal atoms and anions are either non-metals or polyatomic ions (ions with more than one atom). Ionic compounds are only solid at room temperatures. The main properties of ionic compounds are: all ionic compounds form crystals, it has a high boiling and melting point, it is hard and brittle, and it conducts electricity when it is dissolved in an aqueous solution. Crystals are formed because the negative and positive charges come together tightly, or stuck, and they stack into groups. Together, they form a distinct crystal shape. High melting and boiling points are major properties of ionic compounds. The temperatures are high because of the way the compound is held together. They are together as crystals and these big blocks of crystals are full of positive-and negative charges all stuck together. As a result, it takes a huge amount of energy to break it apart.
