Give students the proton, neutron and electron numbers of lithium as an example. Ask students to use three difference colors of clay to form three balls for the electrons, three more for the neutrons and another three for the protons. Instruct them to gently push the proton and neutron balls together to create the atom's nucleus. Also, show them how to arrange the electrons into two energy levels. Afterward, half the classroom's students must remove one electron from their model and add it to a classmate's model. This way, half the class gets a lithium cation model and the other half a lithium anion model.
Write a random chemical symbol on the board, such as "Ne" for neon. Add its mass number, which is the number of protons plus neutrons, on the top left of the symbol and its atomic number, the number of protons, below the mass number. On the right of the symbol, add "+" for the cations and "-" for the anions. Explain that if the atom had lost or gained a second electron, you would have to write "2+" or "2-." Afterward, ask children to write the atomic symbol of the lithium ion in front of them, to check if they have understood the use of atomic symbols.
Write down a list of ions' atomic symbols. Make a copy for each student and distribute the papers to students, with the blank page facing up. Explain to students that they must use the atomic symbols to determine the number of electrons on each ion. For example, nitrogen has an atomic number of 7, which means it has seven protons and seven electrons. But a nitrogen cation with "3+" on its atomic symbol is missing three electrons and therefore, it currently has four electrons (7 - 3 = 4). When everyone is ready, ask students to turn the page and try to find the number of electrons as fast as they can.
Elements are divided into seven groups, according to the number of electrons they have on their outer shell. If the number of electrons is between one and three, the atoms tend to lose the electrons and become cations. If the number of electrons on the outer shell is between five and seven, they tend to attract new electrons and become anions. Elements in Group IV tend not to form ions. Give students the atomic symbol of an element, along with group it belongs to and ask them to write what type of ion the atom tends to become. For example, aluminum is on the third group, so it tends to become a "3+" cation. See the Resources section for more information on the elements of each group.