This is a great activity to incorporate an artistic element into your science work. Each student is assigned an element and they are to create a diagram or picture showing the protons, neutrons, and electrons (in their shells). You may decide how detailed you want to get with the accuracy of the valence electrons.
Below each picture, students are asked to include an index card with facts about their element. The pictures and cards can be mounted on color-coded construction paper (for solids, liquids, and gases, or you could do metals, noble gases, halogens, etc.). Once complete, I have used a large common space to construct a giant periodic table on the wall. Using 9 by 12-inch construction paper, you need a space about 9 by 14 feet for the whole table.
I have included directions for the students, and a rubric.
In the past, I have used the noble gases to explain the number of electrons in each full electron shell. This is a simplification. I have also included a PDF of a periodic table that shows the likely arrangement of electrons for each element. This is not my periodic table, but it is available for use online at wikimedia commons (http://commons.wikimedia.org/wiki/File:Periodic_table_of_elements_showing_electron_shells.png). If your students have computer access for their element research, Genson Science is another excellent resource for information about each element and the electron arrangements.
Often I will present the idea of valence electrons and electron shells using the noble gases to show that these elements are unreactive because they have full outer electron shells. Based on the atomic numbers of the noble gases, we can expect that the electrons shells hold a maximum of 2, 8, 8, 18, 18, 32, and 32 electrons, from the inner to the outermost shells. In reality, the outermost electrons do not follow this arrangement exactly, so you may want to refer to the periodic table showing the actual electron arrangements.
I feel strongly that I do not want any student of mine to have to unlearn something I taught them. So I have given a lot of thought to how to explain the actual arrangement of the valence electrons without over complicating things. If you decide to simplify your explanation of the arrangement of the valence electrons, be sure to let students know that we are still learning about the reactivity of elements and their atomic structure, and that things are more complicated than it first appeared to the scientists who were first constructing the table.
The history of the Periodic Table is fascinating, and if you are interested, The Disappearing Spoon by Sam Kean is an excellent book about the history of the table and the scientists who helped develop it.