How do you determine the number of each type of ion in the compound made of sodium and sulfur? What is the formula of the compound?
The ratio of
The formula is
You must determine the charges on the ions that form the compound. You can often find this by using the Periodic table, or you can look them up in standard lists.
The goal is to ensure that the compound will be electrically neutral, as you state in the question. With a +1 charge on the Na ion and a -2 charge on the sulfide ion, the simplest ratio that results in zero neet charge is 2 to 1.
Use these values as the subscripts in the formula, and you will be writing the empirical formula of the compound (which is what you want!).