This Excel file, (expires 6/22) allows the student to practice writing formulas for ionic compounds formed from ions in main groups 1-3 and 5-7 in the periodic table. This is a helpful introductory exercise for ionic compounds. Note that the formatting is unique to Excel, and so the student must open as an Excel file. If the file is not opened in Excel, the cells will not turn color as designed. Students must use the periodic table to identify the charges on the cations for each row and the a