Iron
Formula: Fe — Iron, ferrum
Appearance: Gray lustrous metal; magnetic
Hazard: Low hazard · Sharp edges on nails/steel wool
Properties
Magnetic. Density 7.87 g/cm³, melting point 1538°C. Reacts slowly with water and oxygen to form rust (hydrated iron(III) oxide, Fe₂O₃·nH₂O). Dissolves in dilute acids with hydrogen evolution. Available as nails, wire, steel wool, or filings. Steel wool has very high surface area and reacts much faster than solid nails — useful for rapid demonstrations.
Historical Context
Iron defined an entire age of human civilization. The transition from bronze to iron tools around 1200 BCE (the Iron Age) transformed agriculture, warfare, and construction worldwide. The chemistry of iron — particularly its two oxidation states Fe²⁺ and Fe³⁺ — was central to early analytical chemistry and pigment-making. Prussian blue, the first synthetic pigment (1704), is an iron coordination compound. Iron gall ink, made from iron and plant tannins, was the dominant writing ink for over a thousand years.
Experiments
Copper Displacement: Drop an iron nail into copper sulfate solution — copper metal deposits on the nail as the blue color fades. Classic demonstration of the activity series.
Rusting in a Bottle: Pack steel wool into a sealed bottle standing in water — oxygen is consumed as iron rusts and water rises to replace it. Demonstrates that air is approximately 21% oxygen.
Experiments using this chemical:
- The Many Colors of Iron - Starting material for the iron compound series
- Copper Reduction - Iron nail displaces copper from solution
Safety
Handle with care — nails and wire have sharp edges; steel wool splinters. Fine steel wool can ignite easily (touch both poles of a 9V battery to a pad as a demonstration). Keep steel wool away from open flames during storage.