Iron

A. Definition
The term iron, as used in the chemical or scientific sense of the word, refers to the chemical element iron or pure iron and is the chief constituent of all commercial iron and steel.

B. Occurance
Iron is believed to be the sixth most abundant element in the universe , formed as the final act of nucleosynthesis by carbon burning in massive stars. While it makes up only about 5% of the Earth's crust, the earth's core is believed to consist largely of an iron-nickle alloy constituting 35% of the mass of the Earth as a whole. Iron is consequently the most abundant element on Earth, but only the fourth most abundant element in the Earth's crust. Most of the iron in the crust is found combined with oxygen as iron-oxide minerals such as hematite and magnetite. About 1 in 20 meteorites consist of the unique iron-nickel minerals taenite (35-80% iron) and kamacite (90-95% iron). Although rare, meteorites are the major form of natural metallic iron on the earth's surface.(Wikipedia)

C. Charateristics

Iron is a metal extracted mainly from the iron ore hematite. It oxidises readily in air and water to form Fe₂O₃ and is rarely found as a free element. In order to obtain elemental iron, and other impurities must be removed by chemical oxygen reduction. The properties of iron can be modified by alloying it with various other metals and some non-metals, notably carbon and silicon to form steels.

Nuclei of iron have some of the highest binding energies per nucleon, surpassed only by the nickle isotope ⁶²Ni. The universally most abundant of the highly stable nuclides is, however, ⁵⁶Fe. This is formed by nuclear fusion in stars. Although a further tiny energy gain could be extracted by synthesizing ⁶²Ni, conditions in stars are unsuitable for this process to be favoured, and iron abundance on Earth greatly favors iron over nickel, and also presumably in supernova element production.

Iron (as Fe²⁺, ferrous ion) is a necessary trace element used by almost all living organisms. The only exceptions are several organisms that live in iron-poor environments and have evolved to use different elements in their metabolic processes, such as manganese instead of iron for catalysis, or hemocyanininstead of hemoglobin. Iron-containing enzymes, usually containing heme prosthetic groups, participate in catalysis of oxidation reactions in biology, and in transport of a number of soluble gases. Seehemoghlobin cythocrome, and catalese.

D. Basic Information

Name	Iron
Symbol	Fe
Atomic Number	26
Atomic Weight	55.845
Standard State	Solid at 298 K
CAS Registry ID	7439-89-6
Group in Periodic Table	8
Period in PeriodicTable	4
Block in Periodic Table	d - Block
Colour	Lustrous, metallic, greyish

Resources :
1. http://en.wikipedia.org
2. http://www.webelements.com