Question

Write the chemical formula of the compound iron [III] oxide in a step-by-step manner.

Answer 1

The symbol of iron is ‘Fe’, having a valency of 3⁺.

The symbol of oxide is ‘O’ with valency 2^-.

Step 1 –

Write the formula of iron [III] oxide:

Symbol Valency

Iron Fe 3⁺

Oxide O 2^-

Step 2 –

Write each symbol with its valency:

Fe³⁺ O^2-

Step 3 –

Interchanging the valencies:

$$\begin{gathered} \mathrm{Fe}\mathrm{O} \\ \searrow \swarrow \\ {3}^{+}{2}^{-} \end{gathered}$$

The formula of the compound iron [III] oxide is Fe₂O₃.