Iron

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Iron is a chemical element with the symbol Fe and atomic number 26. It is the most commonly used metal for industrial applications due to its strong physical properties and abundance. Iron is a crucial component in the formation of steel, which is a key material in construction, transportation, and other industries. Additionally, iron is vital for biological functions; it plays a significant role in carrying oxygen in blood cells. For example, iron deficiency can lead to anemia, a condition characterized by fatigue and weakness due to a lack of adequate healthy red blood cells.

Iron (Wikipedia)

Iron is a chemical element; it has the symbol Fe (from Latin ferrum 'iron') and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust, being mainly deposited by meteorites in its metallic state.

Iron, 26Fe
Pure iron chips with a high purity iron cube
Iron
Pronunciation/ˈərn/
Allotropessee Allotropes of iron
Appearancelustrous metallic with a grayish tinge
Standard atomic weight Ar°(Fe)
Iron in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Fe

Ru
manganeseironcobalt
Atomic number (Z)26
Groupgroup 8
Periodperiod 4
Block  d-block
Electron configuration[Ar] 3d6 4s2
Electrons per shell2, 8, 14, 2
Physical properties
Phase at STPsolid
Melting point1811 K ​(1538 °C, ​2800 °F)
Boiling point3134 K ​(2861 °C, ​5182 °F)
Density (at 20° C)7.874 g/cm3
when liquid (at m.p.)6.98 g/cm3
Heat of fusion13.81 kJ/mol
Heat of vaporization340 kJ/mol
Molar heat capacity25.10 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1728 1890 2091 2346 2679 3132
Atomic properties
Oxidation statescommon: +2, +3
−4,? −2, −1, 0,? +1, +4, +5, +6, +7
ElectronegativityPauling scale: 1.83
Ionization energies
  • 1st: 762.5 kJ/mol
  • 2nd: 1561.9 kJ/mol
  • 3rd: 2957 kJ/mol
  • (more)
Atomic radiusempirical: 126 pm
Covalent radiusLow spin: 132±3 pm
High spin: 152±6 pm
Van der Waals radius194 [1] pm
Color lines in a spectral range
Spectral lines of iron
Other properties
Natural occurrenceprimordial
Crystal structureα-Fe: ​body-centered cubic (bcc) (cI2)
Lattice constant
Body-centered cubic crystal structure for α-Fe: iron
a = 286.65 pm (at 20 °C)
Crystal structureγ-Fe (912–1394 °C): ​face-centered cubic (fcc) (cF4)
Lattice constant
Face-centered cubic crystal structure for γ-Fe (912–1394 °C): iron
a = 364.68 pm (at 916 °C)
Thermal expansion12.07×10−6/K (at 20 °C)
Thermal conductivity80.4 W/(m⋅K)
Electrical resistivity96.1 nΩ⋅m (at 20 °C)
Curie point1043 K
Magnetic orderingferromagnetic
Young's modulus211 GPa
Shear modulus82 GPa
Bulk modulus170 GPa
Speed of sound thin rod5120 m/s (at r.t.) (electrolytic)
Poisson ratio0.29
Mohs hardness4
Vickers hardness608 MPa
Brinell hardness200–1180 MPa
CAS Number7439-89-6
History
Discoverybefore 5000 BC
Symbol"Fe": from Latin ferrum
Isotopes of iron
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
54Fe 5.85% stable
55Fe synth 2.73 y ε 55Mn
56Fe 91.8% stable
57Fe 2.12% stable
58Fe 0.28% stable
59Fe synth 44.6 d β 59Co
60Fe trace 2.6×106 y β 60Co
 Category: Iron
| references

Extracting usable metal from iron ores requires kilns or furnaces capable of reaching 1,500 °C (2,730 °F), about 500 °C (932 °F) higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age. In the modern world, iron alloys, such as steel, stainless steel, cast iron and special steels, are by far the most common industrial metals, due to their mechanical properties and low cost. The iron and steel industry is thus very important economically, and iron is the cheapest metal, with a price of a few dollars per kilogram or pound.

Pristine and smooth pure iron surfaces are a mirror-like silvery-gray. Iron reacts readily with oxygen and water to produce brown-to-black hydrated iron oxides, commonly known as rust. Unlike the oxides of some other metals that form passivating layers, rust occupies more volume than the metal and thus flakes off, exposing more fresh surfaces for corrosion. Chemically, the most common oxidation states of iron are iron(II) and iron(III). Iron shares many properties of other transition metals, including the other group 8 elements, ruthenium and osmium. Iron forms compounds in a wide range of oxidation states, −4 to +7. Iron also forms many coordination compounds; some of them, such as ferrocene, ferrioxalate, and Prussian blue have substantial industrial, medical, or research applications.

The body of an adult human contains about 4 grams (0.005% body weight) of iron, mostly in hemoglobin and myoglobin. These two proteins play essential roles in oxygen transport by blood and oxygen storage in muscles. To maintain the necessary levels, human iron metabolism requires a minimum of iron in the diet. Iron is also the metal at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals.

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