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Iron

physical science Maturity 7-9 Vital Level 3 Next article →

Iron is a very important metal found all over our world. It is a chemical element with the symbol Fe and the atomic number 26. By mass, it is the most common element on our planet. Much of Earth's inner and outer core is made of iron.

Widmanstatten hand
Widmanstatten hand

This huge amount of metal helps create the magnetic field of the Earth. It is also the fourth most common element in the Earth's crust. Without iron, our planet would look and act very differently.

When iron meets water and oxygen, a thing that happens is called oxidation. This process creates brown or black substances called hydrated iron oxides, which we call rust.

Iron(II)-sulfate-heptahydrate-sample
Iron(II)-sulfate-heptahydrate-sample

Rust is different from the layers on some other metals. When rust forms, it takes up more space than the original metal. Because it is bulky, the rust flakes off the surface. This exposes fresh metal to the air so the metal can keep to corrode. Pure iron surfaces look like a smooth, silvery-gray mirror before they rust.

Humans learned to use this metal a long time ago. People in Eurasia started to master working with iron during the 2nd millennium BC. Around 1200 BC, iron tools and weapons began to replace older tools made of copper alloys.

1255 - Keramikos Museum, Athens - Iron tool - Photo by Giovanni Dall'Orto, Nov 12 2009
1255 - Keramikos Museum, Athens - Iron tool - Photo by Giovanni Dall'Orto, Nov 12 2009

This big change is known as the move from the Bronze Age to the Iron Age. Today, we use iron to make many different alloys. These are mixtures of metals like steel and stainless steel. These metals are very common in industry because they are strong and have a low cost.

Iron is also a vital part of how living things work. An adult human body contains about 4 grams of iron.

Heme B
Heme B

Most of this iron lives in two important proteins called hemoglobin and myoglobin. Hemoglobin helps your blood carry oxygen through your body. Myoglobin helps your muscles store that oxygen for use. Because your body needs these proteins, you must get enough iron from the food you eat. This is part of how your body manages its iron metabolism.

In space, iron is a very common and special element. It is the sixth most abundant element in the entire universe.

Ironattenuation
Ironattenuation

Huge stars create iron during their lives through a process called fusion. When these massive stars explode as supernovae, they scatter iron into space. This iron eventually becomes part of new planets and asteroids. Even the cores of other planets, like Mars or the Moon, are believed to be made mostly of iron. It is truly a building block of the cosmos.

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🖼️ Images & Media (26)
File:Iron-alpha-pV.svg
Iron-alpha-pV.svg
File:Pure iron phase diagram (EN).svg
Pure iron phase diagram (EN).svg
File:Magnetization curves.svg
Magnetization curves.svg
File:Ironattenuation.PNG
Ironattenuation.PNG
File:Widmanstatten hand.jpg
Widmanstatten hand.jpg
File:Roussillon_sentier_des_ocres2.JPG
Roussillon_sentier_des_ocres2.JPG
File:Outcropping banded iron formation - panoramio.jpg
Outcropping banded iron formation - panoramio.jpg
File:Pourbaix Diagram of Iron.svg
Pourbaix Diagram of Iron.svg
File:Iron(III) chloride hexahydrate.jpg
Iron(III) chloride hexahydrate.jpg
File:Ferrate_and_permanganate_solution.jpg
Ferrate_and_permanganate_solution.jpg
File:Iron(II)-sulfate-heptahydrate-sample.jpg
Iron(II)-sulfate-heptahydrate-sample.jpg
File:2-isomers-of-ferrioxalate.svg
2-isomers-of-ferrioxalate.svg

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