Page 20 - Curriculum Visions Dynamic Book

For more on iron, see Volume 4: Iron, Chromium, and Manganese in the Elements set.
 Steel is purified iron with controlled amounts of other compounds added to give it useful properties.
Technology
Iron is the most easily obtained, plentiful,
and cheapest of all of the metals. Pure iron is rarely used because it corrodes so easily and is too soft. It is usually alloyed with carbon and other metals to make steel. Pig iron is an alloy containing about 3% carbon but also several non-metallic impurities. It is hard and brittle. It is the material produced by a blast furnace. Wrought iron contains less than 1% carbon, is not brittle and can be forged into shapes.
Geology
Iron is too reactive to occur as a native metal on the Earth’s surface. It is found in the Earth’s core and in stars. It is also found in compounds in the mantle and crust.The most common ore is haematite (iron (II) oxide, Fe2O3).
Biology
Iron is a vital element in all living things. It is particularly important for the oxygen-carrying blood cells as haemoglobin. Iron deficiency leads to anaemia, while an excess leads to kidney and liver damage.
 Gateway Arch, St. Louis, Missouri, is clad in stainless steel and shows how iron can be used to make large, strong structures in interesting shapes.
Red blood cell
 The hemoglobin in our red blood cells contains iron compounds that contribute to their red colour and aid the transfer of oxygen to and from the bloodstream to our body tissues.
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