Iron
Iron, symbolized as Fe, is a chemical element with atomic number 26. It is a metal that belongs to the first transition series and group 8 of the Periodic Table. Iron is the fourth most common element in Earth's crust, making up about 5% of its weight, and is the most common element by mass in the entire planet, forming much of Earth's outer and inner core.
Properties
- Atomic Mass: 55.845 u
- Density: 7.874 g/cm³ at 20°C
- Melting Point: 1538°C (2800°F)
- Boiling Point: 2861°C (5182°F)
- Color: Silvery gray
History
The history of Iron usage dates back to ancient times. Evidence suggests that meteoritic iron was used by humans as early as 3500 BC. Smelted iron appeared around 1200 BC in the Middle East, marking the beginning of the Iron Age. This period saw iron replacing bronze in tools and weapons due to its superior strength, abundance, and the relative ease with which it could be worked when heated.
Extraction and Production
Iron is typically extracted from iron ore, primarily hematite (Fe2O3) and magnetite (Fe3O4). The process involves:
- Mining: Iron ore is mined from open pits or underground.
- Concentration: The ore is concentrated through crushing, grinding, and separating processes.
- Smelting: Iron ore, coke (a source of carbon), and limestone are smelted in a blast furnace. The limestone acts as a flux, helping to remove impurities, which form slag that floats on top of the molten iron and is later removed.
- Refining: The resulting pig iron is further refined to produce steel or wrought iron through various processes like the Bessemer process or basic oxygen steelmaking.
Uses of Iron
Iron has numerous applications due to its strength, malleability, and affordability:
- **Construction:** Iron beams, rods, and other forms are used extensively in construction.
- **Transportation:** Iron is used in vehicles, ships, and railroads.
- **Household Appliances:** Many appliances like refrigerators, washing machines, and cooking utensils are made with iron or steel.
- **Machinery:** Iron is critical in the manufacturing of machinery and heavy equipment.
- **Magnetism:** Iron can be magnetized, making it useful in electrical devices and magnets.
Biological and Environmental Impact
Iron is essential for life, playing key roles in:
- **Biological Processes:** It's a central component of hemoglobin in blood, which carries oxygen in vertebrates, and in many enzymes.
- **Soil and Plants:** Iron is vital for plant growth, though its deficiency or excess can lead to soil and plant health issues.
Sources
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