Properties and Applications of Iron
| Appearance | lustrous metallic with a grayish tinge |
| Standard atomic weight A(Fe) | 55.845(2)[1] |
| Atomic number (Z) | 26 |
| Group | group 8 |
| Period | period 4 |
| Block | d-block |
| Element category | transition metal |
| Electron configuration | [Ar] 3d6 4s2 |
| Electrons per shell | 2, 8, 14, 2 |
Iron has an atomic number 26 with an element symbol Fe (Ferrum) and it’s the first metal of the transition series.Not only Iron can be easily found on the earth core and the surface of it but also it is the most common metal on the earth surface. In addition, from all the other metal from the list, Iron is the fourth common element found on the earth surface.
Like the other groups 8 elements, ruthenium and osmium, iron exists to have in a wide range of oxidation states, −2 to +7, although +2 and +3 are the more common. Elemental iron occurs in shooting stars and other less oxygen environments, but it gets charged up with oxygen and water. Fresh iron surfaces appear shinny silvery-gray but oxidize in standard air environment to give hydrated iron oxides, most commonly known as rust. Unlike the metals that form passivity oxide layers, iron oxides occupy supplementary volume than the metal and thus flake off, exposing fresh surfaces production for corrosion.
Industrial routes
For a limited method when it is needed, pure iron is produced in the laboratory in less quantities by reducing the amount of pure oxide or hydroxide with hydrogen or forming iron pent carbonyl and heating it to 250 °C so that it decomposes to form pure iron powder. Other method is electrolysis of ferrous chloride onto an iron cathode
Blast furnace processing
In the furnace, the coke reacts with O2 in the air blast to create CO (Carbon monoxide):
2 C + O2 → 2 CO
The carbon monoxide reduces the iron ore (in the chemical equation below, hematite) to molten iron, transforming to carbon dioxide in the process:
Fe2O3 + 3 CO → 2 Fe + 3 CO2
2 Fe2O3 + 3 C → 4 Fe + 3 CO2
CaCO3 → CaO + CO2
CaO + SiO2 → CaSiO3
Direct iron reduction
Two major reactions contain the direct reduction process:
2 CH4 + O2 → 2 CO + 4 H2
Fe2O3 + CO + 2 H2 → 2 Fe + CO2 + 2 H2O
Silica is discarded by adding a limestone flux as described above.
Characteristics
| Physical properties | |
| Phase at STP | solid |
| Melting point | 1811 K (1538 °C, 2800 °F) |
| Boiling point | 3134 K (2862 °C, 5182 °F) |
| Density (near r.t.) | 7.874 g/cm3 |
| when liquid (at m.p.) | 6.98 g/cm3 |
| Heat of fusion | 13.81 kJ/mol |
| Heat of vaporization | 340 kJ/mol |
| Molar heat capacity | 25.10 J/(mol·K) |
| Vapor pressure |
Mechanical properties
Chemistry and compound
It forms compounds mainly in the +2 and +3 oxidation states. Usually, iron (II) compounds called ferrous, and iron(III) compounds ferric. It also occurs in top oxidation states, e.g. the purple potassium ferrate (K2FeO4), which has iron in its +6-oxidation state. Although iron(VIII) oxide (FeO4) has been claimed, the result could not be produced again and such a species (at least with iron in its +8-oxidation state) has been found to be unlikely computationally. But, one form of anionic [FeO4]– with iron in its +7-oxidation state, along with an iron(V)-peroxo isomer, has been found by infrared spectroscopy at 4 K after co condensation of laser-ablated Fe atoms with a mixture of O2/Ar.Iron (IV) is a general intermediate in many biochemical oxidation reactions. Numerousorgano iron compounds have formal oxidation states of +1, 0, −1, or even −2. The oxidation states and other bonding properties are often studied using the technique of Mössbauer spectroscopy.Many mixed valence compounds contain togetheriron (II) and iron (III) centers, such as magnetite and Prussian blue (Fe4(Fe [CN]6)3).The last is used as the traditional "blue" in blueprints.
Iron stands first of the transition metals that isunable to reach its group oxidation state of +8, although its heavier congener’s ruthenium and osmium can, with ruthenium having more difficulty than osmium. Ruthenium exhibits an aqueous cationic chemistry in its low-down oxidation states parallel to that of iron, but osmium does not, favoring high oxidation states in which it forms anionic complexes. In the other half of the 3d transition series, vertical similarities least on the groups compete with the horizontal similarities of iron with its neighbor’s cobalt and nickel in the periodic table, which are ferromagnetic at room temperature and contribute to similar chemistry. As such, iron, cobalt, and nickel are sometimes combined as the iron triad.
Applications
The following are the application areas of iron:
FAQs on Iron
1. What are the fundamental properties of the element iron (Fe)?
Iron is a chemical element with the symbol Fe and atomic number 26. As a metal in the first transition series, it exhibits key properties such as malleability, ductility, and high tensile strength. Its electronic configuration, [Ar] 3d⁶ 4s², allows it to form compounds in multiple oxidation states, most commonly +2 (ferrous) and +3 (ferric). It is also known for its magnetic properties, specifically being ferromagnetic.
2. Why is the chemical symbol for iron 'Fe' and not 'Ir'?
The chemical symbol 'Fe' for iron originates from its Latin name, 'ferrum'. Many elements known since ancient times have symbols derived from their Latin or Greek names. The symbol 'Ir' is already assigned to another element, Iridium, which prevents any confusion in the periodic table and chemical formulas.
3. What are the most important industrial uses of iron?
Iron is the most widely used metal, primarily because it is the main component of steel, its most important alloy. Its major industrial applications include:
- Construction: Used to create reinforced concrete, structural beams, and girders for buildings and bridges.
- Automotive and Machinery: Forms the engine blocks, chassis, and various parts of vehicles and heavy machinery.
- Manufacturing: Essential for producing tools, appliances, and industrial equipment.
- Pipelines: Cast iron pipes are used for water and gas distribution due to their durability.
4. What is the chemical process of rusting, and why is it a problem?
Rusting is the common term for the corrosion of iron and its alloys. It is an electrochemical process that requires the presence of both oxygen and water. Iron oxidises to form hydrated iron(III) oxide (Fe₂O₃·nH₂O), a reddish-brown, flaky substance. This is a significant problem because rust is brittle and porous, offering no protection to the underlying metal. This causes the iron structure to weaken, lose its strength, and eventually disintegrate.
5. How does iron's electronic configuration lead to its common oxidation states of +2 and +3?
Iron's electron configuration is [Ar] 3d⁶ 4s². It achieves its first common oxidation state, Fe²⁺ (ferrous), by losing the two electrons from its outermost 4s orbital. It can then lose one more electron from the 3d orbital to achieve the Fe³⁺ (ferric) state. This second ionisation is favourable because it results in a more stable, half-filled d-orbital with the configuration [Ar] 3d⁵, explaining why both +2 and +3 oxidation states are prevalent in its chemistry.
6. What is the key difference between steel, cast iron, and wrought iron?
The primary difference between these three common forms of iron lies in their carbon content, which drastically alters their properties.
- Cast Iron: Has a high carbon content (over 2%). This makes it hard and brittle, but easy to cast into shapes.
- Wrought Iron: Has a very low carbon content (less than 0.08%). It is tough, malleable, and ductile but not as strong as steel.
- Steel: Has a carbon content between that of cast and wrought iron (typically 0.002% to 2.1%). This balance makes steel exceptionally versatile, combining hardness, strength, and workability.
7. From a chemical perspective, why is iron crucial in biological systems like hemoglobin?
Iron's biological importance stems from its ability to easily and reversibly switch between its Fe²⁺ (ferrous) and Fe³⁺ (ferric) oxidation states. In hemoglobin, the iron atom exists in the Fe²⁺ state at the centre of a heme group. This specific state allows it to bind with an oxygen molecule (O₂) in the lungs. When it travels to tissues that need oxygen, it releases the O₂ molecule, a process facilitated by the subtle changes in its coordination chemistry. This efficient oxygen transport is only possible due to iron's unique electronic properties.
8. Why do many iron compounds appear coloured?
As a transition metal, iron has a partially filled d-orbital. In its compounds, these d-orbitals split into different energy levels. When light passes through a solution containing an iron compound (like Fe²⁺ or Fe³⁺ ions), electrons in the lower-energy d-orbitals can absorb photons of a specific wavelength (colour) to jump to a higher-energy d-orbital. This phenomenon is known as a d-d transition. The colour we perceive is the complementary colour of the light that was absorbed. For example, hydrated Fe³⁺ ions often appear yellow or brown because they absorb light in the blue-violet region of the spectrum.
