Fe2O3 compound name
Result: Fe2O3 is iron(III) oxide (also called ferric oxide).
Why the name is iron(III) oxide
Fe2O3 is a binary ionic compound: iron (Fe) is a metal that forms cations, and oxygen (O) is a nonmetal that forms oxide anions. Oxygen almost always has charge 2− in simple ionic compounds (oxide, O2−).
Step 1: Assign the anion charge
Oxygen in oxides is O2−. With three oxygens, the total negative charge is: \[ 3 \cdot (-2) = -6 \]
Step 2: Determine the iron oxidation state
A neutral formula unit has total charge \(0\). Let iron’s oxidation state be \(x\). With two Fe atoms: \[ 2 \cdot x + 3 \cdot (-2) = 0 \] \[ 2x - 6 = 0 \quad \Rightarrow \quad 2x = 6 \quad \Rightarrow \quad x = +3 \]
Step 3: Apply ionic naming rules
For transition metals that can form more than one cation, the metal’s charge is written as a Roman numeral in parentheses:
| Part | Species | Charge / oxidation state | Name used in compound |
|---|---|---|---|
| Cation | Fe | \(+3\) | iron(III) |
| Anion | O | \(-2\) | oxide |
| Combined | Fe2O3 | Total charge \(0\) | iron(III) oxide |
Visualization: charge balance that leads to Fe2O3
Common mistake to avoid
The Roman numeral in iron(III) oxide refers to iron’s oxidation state (\(+3\)), not the subscript “2” in Fe2O3. Subscripts come from charge balance; Roman numerals come from the cation’s charge.