|Atomic mass||55.847 amu|
Iron gets its symbol from its Latin name, ferrum. It is the fourth most abundant element and was first utilized by prehistoric man. The oldest iron artifacts, which are bits of smelted iron, have been dated at 3000 B.C.
Iron is described as a moderately heavy, hard, malleable, and ductile metal. In its pure form, it is a silvery-white colour. One of the most distinctive features is its ability to take and retain a magnetic field.
Iron is the most plentiful, least expensive, and most useful of all metals. The Egyptians knew how to mine, refine and work iron. In the Old Testament, there are numerous references to iron mines, furnaces and iron objects. Unfortunately, iron objects corrode, so evidence for ancient application is written, rather than direct evidence.
Commercial iron is obtained from ores such as hematite, Fe2O3, and magnetite, Fe3O4. Both of these oxides can be broken down into iron and oxygen by heating them in a blast furnace.
Hematite is the chief ore of iron. It is grey in colour. But when exposed to oxygen, it turns rusty colour. One of the largest beds is at Lake Superior in North America. Finely powdered hematite was once used as a skin make up.
Magnetite is another important ore of iron. It is black and magnetic.
Molten iron can dissolve carbon, thus producing an alloy better known as steel. Commercial steels use carbon in proportions anywhere between 0.3 and 1.5%.
The higher the percentage of carbon, the harder the steel becomes. Steel is the most common structural metal used from simple nuts and bolts to the framework of tall skyscrapers.
Some common compounds of iron include:
- rust, a reddish brown substance that is formed. It is a hydrated oxide and has the formulaFe2O3.xH2O. Rusts form when iron and most iron alloys can corrode in the presence of air and moisture.
- ferrous chloride, FeCl2, a colorless crystalline substance that is used in the textile industry to make dyes colorfast.
- ferric chloride, FeCl3, a dark-colored crystal that is used as a disinfectant and in the processing of industrial waste products.
- ferrous sulfide, FeS, a mineral that is found in nature. It is used in the manufacture of hydrogen sulfide, H2S.
- ferrous sulfate, FeSO4, a green crystalline substance that is used in the treatment of iron-deficiency anemia.
- haemoglobin, an iron-protein complex whose chief function is to transport oxygen in the blood stream.