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.
BaSO4 and AgCl are ionic compounds, but their solubility in water is so slight that their solutions do not conduct. When water-soluble ionic compounds do conduct electricity, it is because ions move in the water solution (the interior circuit) from cathode to anode, while electrons move from anode to cathode through a wire in the exterior circuit. It is not just dissolved ion compounds. For it to conduct electricity, it must be an acid or base ionized in water. Hydronium ions (H30+) or the hydroxyl (OH-) ions will be liberated from its corresponding cations (+) or anions (-) by 'breaking bonds' with them.