Iron(III) oxide
Formula: Fe+O2 --> Fe2O3
Chemical Bonding: electro-chemical reactions
Iron(III) oxide is the inorganic compound with the formula Fe2O3 oxygen forms chemical bonds with almost all other elements at elevated temperatures to give corresponding oxides. However, some elements readily form oxides at standard conditions for temperature and pressure; the rusting of iron is an example. The surface of metals like aluminium and titanium are oxidized in the presence of air and become coated with a thin film of oxide that passivates the metal and slows further corrosion.
Chemical reaction between iron and oxygen, which is given by the formula 4Fe + 3O2 = 2Fe2O3. This formula shows that when iron is found in the presence of oxygen, the two chemicals join together to form a new compound. This reaction is called an oxidation/reduction reaction and represents the other (along with acid/base reactions) most common type of chemical reaction. In an acid / base reaction, a proton (H+) gets transferred from one substance to another. In an oxidation/reduction reaction electrons get transferred from one substance to another. In this reaction iron transfers some of its electrons to oxygen. The iron atom becomes an Fe+3 ion and oxygen becomes an 0-2 ion, which quickly joins with an H+ ion to form water. These two elements combine to form iron oxide, or rust.
During the corrosion process, iron does not seem to react with air at all. Water is necessary for the oxidation reaction to occur, to facilitate transport of the electrons.
When iron exceeds the required amount, it is stored in the liver of the human body. The bone marrow contains high amounts of iron, because it produces haemoglobin.
Iron deficits lead to anaemia, causing tiredness, headaches and loss of concentration. The immune system is also affected. In young children this negatively affects mental development, leads to irritability, and causes concentration disorder. Young children, pregnant women and women in their period are often treated with iron (II) salts upon iron deficits.
When high concentrations of iron are absorbed, for example by haemochromatose patients, iron is stored in the pancreas, the liver, the spleen and the heart. This may damage these vital organs. Healthy people are generally not affected by iron overdose, which is also generally rare.
Iron compounds may have a more serious effect upon health than the relatively harmless element itself. A number of iron chelates may be toxic, and the nerve toxin iron penta carbonyl is known for its strong toxic mechanism. Iron dust may cause lung disease.
http://en.wikipedia.org/wiki/Iron(III)_oxide
http://en.wikipedia.org/wiki/Rust
http://answers.yahoo.com/question/index?qid=20100224160556AASHTCr
http://www.blurtit.com/q857020.html
http://wiki.answers.com/Q/What_type_of_chemical_reaction_occurs_when_iron_rusts
http://www.lenntech.com/periodic/water/iron/iron-and-water.htm
http://answers.yahoo.com/question/index?qid=20080423163341AA0CB5c
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