Iron
Symbol: Fe
Atomic Number: 26
Atomic Mass: 55.845 amu (atomic mass units)
Melting Point: 1535.0 C (1808.15 K, 2795.0 F)
Boiling Point: 2750.0 C (3023.15 K, 4982.0 F)
Number of Protons: 26
Number of Electrons: 26
Number of Neutrons: 30
Classification: Metal
Crystal Structure: Cubic
Density @ 293 K: 7.86 grams per cubic centimeter
Color: Silver
Iron has been known for many thousands of years. Artifacts made from smelted iron metal have been dated to 3000 BCE. The name comes from the Anglo-Saxon name for the metal “iren” or “iron”. Its symbol “Fe” comes from the Latin “ferrum” this was the Roman word for the metal.
Pure iron is very reactive and will corrode if in contact with air or moisture. This can be seen in the rapid rusting of a vehicle’s bodywork if the paintwork of a car is damaged. The metal also has magnetic properties. Repeated blows to a piece of iron can induce a magnetic field in the metal. This is a problem in shipbuilding and vessels have to be degaussed to remove residual magnetism and allow a ship’s compass to be used accurately.
Iron is a very common metal. It makes up about 5.3 % of the earth’s crust as well as much of the earth’s core. Iron is also found in our sun and many other stars.
The element is vital biologically. It is an important part of hemoglobin in animals and chlorophyll in plants. Anemia, a deficiency in hemoglobin, can be treated using iron sulfate.
There are four naturally occurring isotopes of iron. Of these iron-54 is unstable with an extremely long half-life the other three isotopes are all stable. The most common isotope is iron-56 at 91.754% followed by iron-54 (5.845%), iron-57 (2.119%) and iron-58 (0.282%). Other unstable isotopes of the element with mass numbers ranging from 45 to 72 are known.
Iron is extracted from mineral ores. The most important sources of iron are the ores magnetite and hematite. Other ores that are commercially viable source of iron include taconite, limonite and siderite.
It is difficult to imagine our world without iron. It is used to make so many things. From the humble paper clip to the locomotive and the tracks along which it runs all owe their existence to iron. Our city sky lines would be totally different without iron to hold up the sky-scrapers.
Because iron is reactive most iron is alloyed to other elements to improve its suitability for use. Steel is the most common alloy it contains between 0.5% and 1.3% carbon. Chromium is added to steel to produce stainless steel. Where steel is required to be used at high temperatures molybdenum or tungsten can be added. If strong but springy steel is needed then vanadium is added to the alloy. Nickel will increase iron’s durability and resistance to acids as well as heat. Manganese can increase the strength of steel and its resistance to wear.
