Notes on Writing Formulas

Rules:
1.Formulas represent the ratio of cations to anions
2.Total charge of ions must add up to zero
3.Subscripts are used to balance the positive and negative charges

Steps to writing formulas:
1.Cation (positive ion) goes first and the anion (negative ion) goes second
2.Check to see if the charges of the ions add up to zero, if they do, you are done. If not, continue to the next step
3.If the charges do not match, then the number of the charges must be switched to the other ion. Write the numbers as subscripts, but don't write one and don't write the sign of the charge.
4.Use parenthesis for polyatomic ions that you needed to add a subscript, but don't use parenthesis if you don't have to