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Facts About Iron

Iron
Credit: Greg Robson/Creative Commons, Andrei Marincas | Shutterstock
Atomic Number: 26
Atomic Symbol: Fe
Atomic Weight: 55.845
Melting Point: 2,800.4 F (1,538 C)
Boiling Point: 5,181.8 F (2,861 C)

Word origin: Iron is an Anglo-Saxon word. The chemical symbol for iron, Fe, is from the Latin word ferrum, which means metal.

Discovery:  Iron has been used as a metal since ancient times and is mentioned in the Old Testament of the Bible. An iron pillar, dating to about A.D. 400, remains standing in Delhi, India.

Properties of iron

Iron is a brittle, hard substance. It is classified as a metal in Group 8 on the Periodic Table of the Elements.

The pure metal form rapidly corrodes when exposed to moist air or high temperatures. Iron gets oxidized when it comes in contact with atmospheric oxygen.

Iron ore
Iron ore oxidizes, or rusts, when it comes in contact with oxygen.
Credit: Denis Selivanov | Shutterstock

Iron has four allotropic forms classified as alpha, beta, gamma and omega. The alpha form of iron is magnetic. However, when adjusted into the beta form, it loses its magnetism.

Varying amounts of sulfur, silicon, manganese and phosphorus make up an alloy called pig iron. Pig iron also contains about 3 percent carbon.

Iron has very stable nuclei. Common iron is a mix of four isotopes, and 10 other isotopes exist.

Sources of iron

Iron is a very common element on Earth and is also found abundantly in the sun and stars.  It is the fourth most common element in the Earth’s crust by weight and much of the Earth’s core is thought to be composed of iron.

Iron is primarily obtained from the mineral hematite, often seen as the black sand along a beach or stream. Other sources are magnetite, siderite and limonite. Siderites are a class of meteorite that contains iron as their main component.

Uses of iron

Iron is an abundant metal that is cheap, useful for many products and important in human history. Iron has been used as a metal since ancient times. Iron is durable, strong and can be easily alloyed with other materials to increase its use.

Steel is an alloy of carbon and iron. It is used to make many modern products, including cars, railways, skyscrapers, guns and ships.

Stainless steel, an alloy with about 10 percent chromium content, is used in kitchen cutlery, appliances and cookware. It does not easily corrode or rust.

Wrought iron, an iron alloy with very small amounts of carbon content, is malleable, less fusible and has a fibrous structure. "Wrought" means to work by hand. Many products that were once wrought, such as garden gates and fence rails, are actually steel, though they keep the description. The Eiffel Tower was constructed from a form of wrought iron.  

Cast iron has been heated to its molten state and then poured into a mold and hardened. It is an important form that is used in manufacturing pots, pans, skillets, ovens and trays.  

Taconite, an iron mineral, is increasingly being used for commercial products. Like most iron minerals, it’s alloyed with carbon to make a usable product.

Iron is also vital to life and carries oxygen in hemoglobin protein of red blood cells. Iron-rich foods include:

  • Meat, including beef, turkey, chicken and pork
  • Seafood, including shrimp, clams, oysters and tuna
  • Vegetables, including spinach, peas, broccoli, sweet potatoes and string beans
  • Fruit, including strawberries, watermelon, raisins and dates
  • Bread and cereals, including bran cereals, whole wheat bread and enriched rice
  • Other foods, including beans, lentils, tomato paste, tofu and molasses.

(Sources: Los Alamos National Laboratory, American Red Cross)

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