1. Show the class pictures of five very different mammals, such as a cat, kangaroo, horse, rabbit, and monkey. Explain that all these animals are mammals, and that mammals constitute one class of the animal kingdom, which also includes other classes, such as reptiles, birds, and fish. Ask students what these five mammals have in common and mark their responses on a sheet of chart paper.
When ionic compounds are in a molten state or dissolved in water, forming an aqueous solution, the ions that formed the ionic compounds are able to move around freely, thus able to conduct electricity.
Properties of ionic compounds: Ionic solids are poor conductors of electricity and heat. Ionic solids are generally high melting (more than 150 degrees C). Ionic solids are hard and brittle. Ionic solids melt to form liquids that are electrical conductors because the ions are free to move. Ionic solids that are water soluble, dissolve to form solutions that are electrical conductors.