Iron Properties of a Transition Metal

Introduction

Iron (Fe), atomic number 26, is the most abundant transition metal in Earth’s crust and a cornerstone of metallurgy and biochemistry. Its versatile oxidation states and magnetic properties make it critical in industry, materials, and life processes.

Occurrence & Extraction

Iron is primarily found as hematite (Fe₂O₃) and magnetite (Fe₃O₄). Extraction involves reduction of these ores in a blast furnace using coke and limestone:

Fe₂O₃ + 3 CO → 2 Fe + 3 CO₂  
Fe₃O₄ + 4 CO → 3 Fe + 4 CO₂

Physical Properties

  • Silvery-gray metal with a slight reddish tinge
  • Melting point: 1538 °C; boiling point: 2862 °C
  • Density: 7.87 g cm⁻³
  • Ferromagnetic below Curie point (770 °C)
  • Malleable, ductile, and good conductor of heat and electricity

Chemical Properties

  • Reactivity with oxygen: Forms rust (hydrated Fe₂O₃) in moist air; protective oxide layer forms at high temperatures.
  • Reaction with acids:
    Fe + 2 HCl → FeCl₂ + H₂↑
  • Reaction with bases: Amphoteric behavior:
    Fe + 2 NaOH + 2 H₂O → Na₂[Fe(OH)₄]
  • Complex formation: Forms numerous coordination compounds (e.g., hexaquoiron(II), hexaquoiron(III)).

Oxidation States

Common oxidation states of iron are +2 and +3:

Oxidation State Species Color
+2 Fe²⁺ Pale green
+3 Fe³⁺ Yellow/brown

Important Reactions

Formation of Rust

4 Fe + 3 O₂ + x H₂O → 2 Fe₂O₃·xH₂O

Redox Between Fe²⁺ and Fe³⁺

Fe³⁺ + e⁻ → Fe²⁺  
Fe²⁺ – e⁻ → Fe³⁺

Applications

  • Steel production (alloys of Fe and C)—foundation of construction and machinery
  • Cast iron and wrought iron for tools, pipes, and engines
  • Hemoglobin contains Fe²⁺ for oxygen transport in blood
  • Catalysts in Haber process (Fe) and Fischer–Tropsch synthesis
  • Magnetic materials and data storage

Conclusion

Iron’s abundance, multiple oxidation states, and magnetic and mechanical properties make it indispensable in technology, construction, and biology. Mastering its chemistry is vital for understanding industrial processes and life’s molecular machinery.

 

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