Writing Ionic Formulas

This video tutorial explains how to write formulas for ionic compounds, which are formed between metals and non-metals or cations and anions. It outlines three basic steps: identifying symbols, determining charges, and balancing them to write the formula. The video provides examples with sodium chloride, magnesium fluoride, chromium phosphide, and aluminum sulfate, demonstrating the application of these steps to create correct ionic formulas.

What does the Roman numeral in the name of a compound indicate, specifically in the case of chromium(II) phosphide?

How do you write the formula for aluminum sulfate, and why is it important to use parentheses?