Question

Solve the below for $\mathrm{Fe}\mathrm{and}\mathrm{S}$.

1. Identify the valency.
2. Crisscross the valency.
3. Write the formula and name of the compound

Answer 1

Step 1: Identifying the valency

Iron is a bivalent cation and hence, the valency is $2$. It means, by losing two electrons the charge becomes +$2$.

Sulphide is a bivalent anion and hence, the valency is $2$. It means, by gaining two electrons the charge becomes $-2$.

Step 2: Crisscrossing the valency

Step 3: Formula and name of the compound

By crisscrossing the valency with the symbol above, the formula is derived as ${\mathrm{Fe}}_2{\mathrm{S}}_2$.

By using the simplest ratio, then the formula becomes $\mathrm{FeS}$.

The chemical name of the compound is Iron (II) sulphide.