Final answer:
The polyatomic ion in Fe(HCO₃)₃ is HCO₃⁻, named hydrogen carbonate or bicarbonate, and the full name of the compound is iron(III) hydrogen carbonate.
Step-by-step explanation:
The formula for the polyatomic ion in Fe(HCO₃)₃ is HCO₃⁻, which is known as the hydrogen carbonate ion or bicarbonate ion. The full name of the compound Fe(HCO₃)₃ is iron(III) hydrogen carbonate. In this formula, there is one Fe³⁺ cation and three HCO₃⁻ anions.
Since iron is a transition metal that can have more than one possible charge, the oxidation state of iron in the compound is indicated by the Roman numeral III in the name of the compound.