The Element Iron

Introduction to Iron

The element iron is a ductile, silver-gray metal that is very reactive with the air around us. It has incredibly strong alloys which are used in diverse areas of manufacturing, construction, and electronics. Iron also plays an important role in the bodies of living organisms, and is even responsible for the red color of our blood.

Ten Interesting & Fun Facts about Iron

1. Iron readily reacts with both oxygen and water to form iron(III)oxide, or ferric oxide, commonly known as rust, in following unbalanced reaction: Fe + O₂  + H₂O → Fe₂O₃H₂O
2. Under a flame test, iron burns a brilliant gold color
3. The element symbol ‘Fe’ comes from iron’s Latin name ‘ferrum,’ meaning ‘firmness.’
4. Iron is the second most abundant metal on earth, second to aluminum
5. The earth’s inner core is believed to be made up primarily of iron and nickel.
6. Pure iron is actually quite soft and ductile like most metals – the addition of carbon and heat rigidifies the iron
7. Iron can be recycled, with tremendous environmental benefits
8. Research shows that Mars’ mantle constitutes twice as much iron as Earth’s, and that the planet’s reddish color is actually rust on Mars’ surface
9. Iron is used to create sparks in fireworks
10. The Iron Range is a collection of iron-mining regions neighboring Lake Superior 

Iron in the Periodic Table

Iron’s element symbol is Fe, and has an atomic number of twenty six. As a transition metal, iron is located in the d-block, specifically in group 8 and period 4. Iron’s electron configuration is [Ar] 3d6 4s2, and thus it has 2 valence electrons. It is a very stable element. Iron’s electronegativity is 1.83 on the Pauling scale.

The Biological Significance of Iron

The element iron is an essential mineral for all living organisms. In animals, iron is used to make hemoglobin, a protein in red blood cells responsible for the transportation of oxygen from the lungs to the rest of the body. Iron is also present in myoglobin, the muscle cells which stores and transports oxygen. Too little iron in animals can lead to anemia, while excess iron can be toxic and damaging to the body. The U.S Daily Recommended Allowance is 18 milligrams of iron. In plants, iron is necessary for the production of chlorophyll.

Alloys of the Element Iron

Iron and carbon form the well-known alloy of steel. Iron is the major alloying agent in ferroalloys, a classification of alloys with less than 50% iron and a high concentration of silicon, manganese, aluminum, nickel, chromium, molybdenum, vanadium, or other elements. Ferroalloys aren’t suitable for independent use; rather, because of their low melting points, they are added to liquid steel to form alloy steel. Depending on the major alloying agent in alloy steel, the metal can have varying chemical properties. For instance Bismuth in steel improves machinability, Silicon increases magnetic properties.

Iron Applications in Today’s World

What is the Element Iron Used For?

Structural Uses of Iron

The element iron is crucial in architectural and structural design. As a key alloying agent, iron is used as a base in the manufacturing of steel, sheet iron, cast iron, and wrought iron. Iron and its alloys are used in a wide array of manufacturing industries, forming key structural components in vehicles, buildings, ships, and other appliances; The element iron can support larger and stronger structures than other building materials, i.e. stone, wood, and brick, with less material and low cost.  Steel is used for buildings, infrastructure, machines, metal stamping, fabrication, and so much more – like steel wool, which is mostly pure iron with a little carbon added.

Iron as a Catalyst

Activated or promoted iron is also used as a catalyst in a variety of chemical industries. Specifically, magnetite, an iron-oxide, is used as a catalyst in the Haber-Bosch process. Iron speeds up a reaction between hydrogen and nitrogen to produce ammonia, a common large-scale industrial process. Furthermore, magnetite is used in Gas-to-Liquid (GTL) processes which turn natural gas into synthetic fuel.

When and How was Iron Discovered?

The History of Iron

Historians and archaeologists believe that the element iron has been used for around five thousand years. While it was occasionally used prior in history, Iron was popularized during the Iron Age (1200 BCE – 600 BCE), the third leg of the Stone-Bronze-Iron Age progression. The Iron Age began in the Mediterranean and Eastern Europe around 1200 BCE, though it only spread to Asian regions closer to 600 BCE. During this time period iron gradually replaced bronze as the primary material of tool and weapon construction; historians suspect that the use of iron became more mainstream once humans popularized the smelting of iron and carbon to create the much stronger steel.

Who Discovered Iron

Not much is known about the particular discovery of iron because it has been used by humans since ancient times. Archaeologists can trace iron-nickel alloyed beads back to 3200 BCE Egypt.

Where is Iron Found in the Universe

Iron is incredibly prominent in nature. It is the fourth most abundant element in the Earth’s crust, and the second metal, behind aluminum, oxygen, and silicon. Iron is also believed to be the primary component of the Earth’s core. Iron is rarely found pure in nature; rather it is found as iron ore, a combined mass of iron and other minerals and elements. The most common ores of iron are: hematite (Fe₂O₃), magnetite (Fe₃O₄), limonite (FeO(OH)·n(H2O)), goethite (FeO(OH)), and siderite (FeCO₃), and taconite.

Iron is also found in the sun, stars, and in meteorites. Fascinatingly, iron can actually be fused in stars’ cores. Helium is the starting base of a star’s core, but if a star is hot enough and releases enough energy, it can gradually fuse the helium to carbon, then to oxygen, then to silicon. If a star is so large that it has a mass of 8-12 times the size of the sun, called a “supergiant,” it has enough energy to fuse its silicon core to iron. At this point the star is releasing massive amounts of energy. However, because the atomic structure of iron is so stable, it cannot be fused further, and the star’s core suddenly cannot maintain its equilibrium. At that point the star will either explode in a supernova or collapse into a black hole.

Iron Chemistry – Compounds, Reactions, Oxidation States

Chemical Properties of Iron Element

The element iron is a very chemically reactive metal, and reacts openly with oxygen in humid air; in fact, free iron is not readily found in nature. Iron dissolves in water, and reacts with steam to form hydrogen gas. Iron also reacts with hydrohalic acids to form ferrous halides. Furthermore, iron forms coordination compounds due to its electronic structure.

Ferromagnetism of Iron

Iron is one of only three metals have ferromagnetic properties under normal conditions (in addition to cobalt and nickel). Most bulk materials are not magnetic because their unpaired electrons spin in opposite directions and cancel out any magnetic properties. But when a ferromagnetic material encounters external magnetic fields, its unpaired electrons actually realign parallel to one another to magnetize the material. Moreover, ferromagnetic metals will actually retain their magnetism after the external force has been removed. This magnetism goes away when a maximum temperature has been reached, known as the Curie temperature.

Why Does Iron Rust

Iron rapidly oxidizes in the presence of air, requiring both oxygen and water as a medium to most frequently form iron(III) oxide (Fe₂O₃) and iron(II,III) oxide (Fe₃O₄). These iron oxides, and more, are collectively known as rust. Iron(II) oxides can form, and are stable as salts, but further oxidize easily to iron(III) salts with hydroxide or oxygen anions. Rusting is not a reversible process, and can cause the metal to expand, thus increasing stress. Iron rusting is inevitable, but measures can be taken to slow the process. A layer of oil will prevent moisture from reaching the metal. Galvanizing the iron, coating it in a thin layer of zinc, will also prevent oxygen and water from reaching the metal. This slows the rusting process.

Iron Oxidation States

The element iron has a diverse range of oxidation states including 0, +2, +3, +4, and +6, but the most common are Fe⁺² (ferrous) and Fe⁺³ (ferric). Pure iron can only be found in low-oxygen environments because of its easy oxidation. Iron can easily switch between the +2 and +3 oxidation states.

Iron Compounds

Since iron is so reactive, it forms many compounds including, but not limited to, oxides, hydroxides, halides, sulfates, sulfides, and chlorides. It most commonly forms bivalent and trivalent compounds, due to its tendency towards the +2 and +3 oxidation states. Some additional compounds beyond oxides are:

Sulfates:

> FeSO₄ (Ferrous Sulfate): In its pure form, ferrous sulfate is used to treat iron deficiency anemia

> Fe₂(SO₄)₃ (Ferric Sulfate): Ferric Sulfate has additional medical benefits. It is commonly employed as a hemostatic agent during surgery.

> FeSO₄·7H2O (Green Vitriol): Ferrous sulfate hepta-hydrate is a green or teal crystalline ferrous sulfate. This is produced by combining dilute sulfuric acid with iron, often created as an industrial byproduct. It is also known as green vitriol and is used in the manufacturing of pesticides and fertilizers.

Chlorides:

> FeCl₂ (Ferrous Chloride): A crystalline yellow-green, ferrous chloride is formed by passing dry hydrogen chloride over hot iron. It can be produced in its liquid form FeCl₂∙4H2O by dissolving solid iron in hydrochloric acid. Ferrous chloride is most commonly employed in the dye industry as a reducing agent. 

> FeCl₃ (Ferric Chloride): Ferric chloride is a colorless or light brown solution widely used as a common chlorinating agent. Dissolving iron ore directly in hydrochloric acid will produce ferric chloride, as will oxidizing iron(II) chloride with chlorine gas.

Sulfides:

> FeS₂ (Pyrite): Also known fools’ gold, pyrite is naturally occurring and abundant in nature. Its lustrous yellow-brass color can lead it to be mistaken for gold; however, its brittle makeup, lack of usability, and widespread availability renders it unprofitable. Pyrite can be distinguished from gold by its rough edges, unlike gold which is much smoother. Fools’ gold also contributed to the Gold Rush of the 1840s.

Isolation of Iron

Iron extraction from iron ore generally takes place in a blast furnace through a redox reaction. Iron ore and, typically, carbon (or carbon monoxide) are placed in a large container together and heated. As the carbon is more reactive, the carbon oxidizes and the iron is reduced to produce liquid iron.

This can be seen in the following reaction:

2Fe₂O₃(s) + 3C(s) → 4Fe(l) + 3CO₂(g)

A similar reaction can also be done with aluminum as the reducing agent, in an exothermic oxidation-reduction called a thermite reaction.

Physical properties of Iron

Iron is a lustrous silver-gray solid metal, which is very ductile in its pure form. 

• Symbol: Fe
• Melting point: 1536 C
• Boiling point: 2861 C
• Density:  7.8 g.cm-3
• Atomic weight: 55.845
• Atomic number: 26
• Electronegativity: 1.83
• Classification: Transition metal, Group 8 metal
• Natural abundance of 5% in the earth’s crust
• Electron shell configuration:[Ar] 3d6 4s2
• Isotopes: 5.845% of ⁵⁴Fe 91.754% of ⁵⁶Fe, 2.119% of ⁵⁷Fe and 0.286% of ⁵⁸Fe.
• Found naturally in the minerals: hematite, magnetite, taconite

Where can I buy Elemental Iron?

Iron can be found online in stores such as Amazon. Iron building materials can also be found in many hardware or home improvement stores. Pure iron powder is easily found online – just make sure you are not actually buying iron oxide or an iron alloy.