Iron Facts – Atomic Number 26 or Fe

Iron is an element that is essential for human life that occurs naturally in pure form as well as alloys. It is in hemoglobin in red blood cells and cast iron cookware. Here are interesting element facts about iron, a transition metal with the element symbol Fe and atomic number 26.

Interesting Iron Facts

1. Iron has been used by humans for over 5,000 years. It has been found in ancient Egyptian artifacts as early as 3,500 BC. However, few ancient iron artifacts survived to the present day because of the metal’s tendency to corrode in water and air.
2. Meteorites often contain high concentrations of iron, giving ancient cultures access to the metal before mining techniques were developed.
3. The element symbol for iron, Fe, comes from Latin name for the element, “ferrum.” The modern name “iron” comes from the Anglo-Saxon word “iron” and the Scandinavian word “iarn.”
4. Iron is a common element on Earth as well as throughout the universe. It is the fourth most abundant element in the Earth’s crust by mass (5.6%) and likely the most abundant element in the planet overall because it accounts for around 85% of the mass of Earth’s inner and outer core. It is the sixth most abundant element in the universe. Iron is the heaviest element formed by fusion in stars.
5. Iron is not always magnetic. The alpha allotrope is ferromagnetic, but the beta allotrope is not.
6. Both animals and plants need iron. Plants use iron in chlorophyll, which is the key pigment for photosynthesis. Human use iron in hemoglobin for transporting oxygen to cells. Some bacteria use iron-sulfur clusters for nitrogen fixation.
7. While iron is an essential nutrient, it is toxic in high amounts. Free iron reacts with peroxides to form free radicals in blood, which can damage protein, lipids, and DNA. Iron is toxic to people at a concentration of 20 mg per kg body weight and lethal at 60 mg per kg body weight.
8. The most common oxidation states of iron are +2 and +3, but several other states also occur.
9. Natural iron consists of four stable isotopes. Of these, iron-56 is the most abundant, accounting for 91.75% of the element. Only iron-57 has a nuclear spin. There are numerous radioisotopes (at least 24).
10. There are four allotropes or forms of iron. They are collectively known as “ferrites” and are the α-, β-, γ-, and δ-allotropes. While the alpha and beta forms have the same crystal structure, they exhibit different properties.
11. Freshly prepared iron is metallic silver, but the element rapidly oxidizes to develop a black coating. Iron burns golden yellow in a flame test. The metal is used in fireworks for this golden color, plus it produces sparks ranging in color from red to yellow to white based on the metal’s temperature.
12. The iron isotope Fe-56 is one of the most stable nuclei, making it resistant to fission or fusion, hence why iron is often the final stage of nuclear reactions in stars.

Discovery, Naming, and Isolation

Iron has been known and used by humans for thousands of years, with early evidence of its use dating back to around 1200 BCE during the Iron Age. It was one of the first metals humans learned to work with, primarily through smelting techniques to extract iron from ores. Blast furnaces developed in the Middle Ages allowed for isolation of the pure element. However, even before this, people made use of iron from meteorites.

The name “iron” comes from Old English “īsern” and its Germanic roots. Its symbol Fe comes from the Latin word ferrum, meaning “iron.”

Appearance and Properties

Iron is typically silvery-gray in appearance and has a lustrous metallic sheen. It is malleable, ductile, and ferromagnetic (able to be magnetized). However, it readily reacts with oxygen and moisture, forming rust (iron oxides), which leads to corrosion.

Allotropes

Iron exists in several allotropes, depending mainly on temperature:

• Alpha iron (ferrite): Stable below 912°C; body-centered cubic (BCC) structure.
• Gamma iron (austenite): Stable from 912°C to 1,394°C; face-centered cubic (FCC) structure.
• Delta iron: Stable between 1,394°C and its melting point (1,538°C); also BCC.
• Epsilon iron: While alpha, gamma, and delta iron occur at ordinary pressures, epsilon iron only forms at a pressure greater than 10 GPa. This form has a hexagonal close-packed (HCP) crystal structure.

There may also be a beta form at pressures above 50 GPa and temperatures over 1500 K. β-iron has an orthorhombic or double HCP structure.

Element Group

Iron belongs to Group 8 (VIIIB) of the periodic table and is a transition metal. It is part of the iron triad, which also includes cobalt (Co) and nickel (Ni). It shares many properties with these elements, particularly their magnetic behavior.

Isotopes of Iron

Natural iron consists of four stable isotopes:

• Iron-54 (5.8%)
• Iron-56 (91.7%) – the most abundant isotope
• Iron-57 (2.1%)
• Iron-58 (0.3%)

There are also several synthetic isotopes, the most notable being Iron-60, which is radioactive with a half-life of 2.6 million years and has applications in radiometric dating of space objects.

Abundance and Sources

Iron is the fourth most abundant element in the Earth’s crust, making up about 5%. It occurs in large quantities in meteorites and is the primary element in the cores of planets like Earth. Major sources of iron include:

• Hematite (Fe₂O₃)
• Magnetite (Fe₃O₄)
• Limonite (FeO(OH)·nH₂O)
• Siderite (FeCO₃)

Iron is also abundant in the universe, produced in large quantities in stars through stellar nucleosynthesis.

Purification

The primary method of purifying iron is through the blast furnace process, where iron ore is reduced using carbon (coke) in the presence of limestone. This removes impurities, resulting in pig iron. Pig iron gets refined into steel or wrought iron through additional processes such as basic oxygen steelmaking (BOS).

Uses of Iron

Iron has countless applications, both historical and modern:

• Construction and infrastructure: Reinforced concrete, bridges, and buildings.
• Manufacturing: Automotive parts, machinery, and tools.
• Steel production: The largest use of iron is in steel, an alloy of iron and carbon.
• Transportation: Railways, ships, and aerospace structures.
• Magnetic materials: In motors, transformers, and magnetic storage devices.
• Catalysis: Iron compounds are catalysts in chemical reactions, such as in the Haber process for ammonia production.
• Biological: Iron is a critical component in hemoglobin for oxygen transport in blood.

Oxidation States of Iron

Iron primarily exists in two oxidation states:

• +2 (ferrous): Fe²⁺ ions
• +3 (ferric): Fe³⁺ ions

Both states participate in various chemical reactions, but iron also forms less common states, ranging from -4 to +7.

Biological Role

Iron is essential for life, particularly for oxygen transport. In humans and animals, iron is a key component of hemoglobin in red blood cells and myoglobin in muscles. It also plays a role in many enzymatic reactions, including DNA synthesis and electron transport in mitochondria.

Health Effects

There are problems with having either too little or too much iron:

• Deficiency: Iron deficiency leads to anemia, characterized by fatigue, weakness, and impaired cognitive function.
• Toxicity: Excessive iron intake leads to conditions like hemochromatosis, which causes tissue damage, liver disease, and heart problems.

Key Facts Table for Scientists

References

• Dlouhy, Adrienne C.; Outten, Caryn E. (2013). “Chapter 8.4 Iron Uptake, Trafficking and Storage”. In Banci, Lucia (Ed.). “The Iron Metallome in Eukaryotic Organisms”. Metallomics and the Cell. 12. Springer. doi:10.1007/978-94-007-5561-1_8. ISBN 978-94-007-5560-4.
• Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
• Meija, J.; et al. (2016). “Atomic weights of the elements 2013 (IUPAC Technical Report)”. Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305
• Weeks, Mary Elvira; Leichester, Henry M. (1968). “Elements Known to the Ancients”. Discovery of the Elements. Easton, PA: Journal of Chemical Education. pp. 29–40. ISBN 0-7661-3872-0.