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.
Electricity is conducted when charges move from one place to another. In metals, the conductivity is due to delocalized electrons that can wander all over the place. You're probably already familiar with this. In solid ionic compounds, on the other hand, the ions aren't going anywhere. The cations and anions all attract themselves into a nice lattice and they're stuck there until they have a better reason to wander off. No moving ions = no electricity. However, if you melt an ionic compound or dissolve it in water, these ions are now free to move around.