Iron pyrite, fes2, is known as fool's gold because it is a shiny yellow solid which is similar in appearance to gold. iron pyrite is an ionic compound. gold is a metallic element.- iron pyrite, fes2, contains positive and negative ions. the positive ion is fe2+.1) what is the formula of the negative ion?

Explanation:

The algebraic sum of all the oxidation numbers of all atoms in a neutral compound is zero.

In order to know the formula of the negative Sulfur ion in pyrite, we must determine its oxidation state.

Let us make the make the oxidation number of sulfur = x

Therefore, FeS₂:

                      +2 +2x = 0

                      +2 = -2x

                       x = -1

The formula of the negative ion is S⁻