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 can only be conducted when ions are freely moving in separate positive and negative charges (as in the aqueous form and molten form). In their crystalline form, the ions in the ionic compound are locked tightly in one place and the positive and negative balance out to make the overall structure neutral. Why do metals and nonmetals usually form ionic compounds, whereas two bonded nonmetals are never ionic?