The useful transition metal ─ Iron

Basic Information  Chemical Symbol :Fe  atomic number 26  The fourth most common element in the earth crust  Oxidation states varies from -2 to +6 +2(green) and +3(Yellow) are the most common  Density (near r.t.) : g·cm−3  Melting point :1538 °C  Boiling point : 2862 °C

Compound of iron  Iron forms compound mainly in +2 or +3 oxidation states Iron(III) compound called ferric and Iron(II) compound called ferrous e.g Fe(II) Sulphate or Fe(III)Sulphate  Iron(IV) is a common intermediate in many in biochemical oxidation reactions  Iron compound with +6 oxidation states Potassium Ferrate (K2FeO4)  The iron compounds produced on the largest scale in industry are iron(II) sulfate (FeSO4·7H2O) and iron(III) chloride (FeCl3). Iron(II) compounds tend to be oxidized to iron(III) compounds in the air.  Iron reacts with oxygen in the air to form various oxide and hydroxide compounds; the most common are iron(II,III) oxide (Fe3O4), and iron(III) oxide (Fe2O3).

Extraction of Iron  Heating metal ore with carbon(carbon reduction)  At high temperature, carbon can react with iron(III) oxide in haematite. In the process, carbon removes the oxygen from iron(III) oxide to form iron  Iron(II,III) oxides +carbon monoxide →iron+ carbon dioxide

Industrial Use  the most widely used metal in the world, in proportion 95% of metal production  Low Cost, High Strength. Important in construction and industrial use  Steel  Iron with a certain proportion of carbon produce through smelting process, this is to strengthened and hardened the pure iron, steel is 1000 times harder than pure iron.  Steel, low carbon iron alloys and alloy steel are commonly used in industry  Iron(II,III) oxide (Fe3O4), and iron(III) oxide (Fe2O3) are used in the production of ferrites, useful magnetic storage media in computers, and pigments.  Iron is used for protection from ionizing radiation. Although it is lighter than another traditional protection material, lead, it is much stronger mechanically.  Stainless steel

Biological use  ranging from the evolutionarily primitive archaea to humans  ecessary trace element found in nearly all living organisms  Iron-containing enzymes and proteins, often containing heme prosthetic groups  mediate redox reactions, and of oxygen carrier proteins such as hemoglobin, myoglobinand leghemoglobin

Disadvantage of iron  suffer badly from rust if not protected in some way  Painting, galvanization, passivation, plastic coating and bluing are all used to protect iron from rust