HIERRO

Introducción

Número atómico: 26
Grupo: 8 or VIII B
Peso atomico: 55.845
Período: 4
Número CAS: 7439-89-6

Clasificación

chalcogen
halógeno
Gas noble
Lantanoides
Actinoides
Elemento de tierras raras
Platino Metal Group
transuranium
No hay isótopos estables
Sólido
Líquido
Gas
Sólido (Predicho)

Descripción • Usos / Función

The use of iron is prehistoric. Genesis mentions that Tubal-Cain, seven generations from Adam, was “an instructor of every artificer in brass and iron.”A remarkable iron pillar, dating to about A.D. 400, remains standing today in Delhi, India. This solid shaft of wrought iron is about 7.25 m high by 40cm in diameter. Corrosion to the pillar has been minimal although it has been exposed to the weather since its erection. Iron is a relatively abundantelement in the universe. It is found in the sun and many types of stars in considerable quantity. Its nuclei are very stable. Iron is found native as a principalcomponent of a class of meteorites known as “siderites, and is a minor constituent of the other two classes. The core of the earth, 2150 miles in radius,is thought to be largely composed of iron with about 10% occluded hydrogen. The metal is the fourth most abundant element, by weight, making upthe crust of the earth. The most common ore is hematite (Fe2O3), which is frequently seen as black sands along beaches and banks of streams. Taconiteis becoming increasingly important as a commercial ore. Common iron is a mixture of four isotopes. Ten other isotopes are known to exist. Iron isa vital constituent of plant and animal life, and appears in hemoglobin. The pure metal is not often encountered in commerce, but is usually alloyedwith carbon or other metals. The pure metal is very reactive chemically, and rapidly corrodes, especially in moist air or at elevated temperatures. Ithas four allotropic forms, or ferrites, known as alpha, beta, gamma, and delta, with transition points at 700, 928, and 1530°C. The alpha form is magnetic, but whentransformed into the beta form, the magnetism disappears although the lattice remains unchanged. The relations of these forms are peculiar. Pig iron isan alloy containing about 3% carbon with varying amounts of S, Si, Mn, and P. It is hard, brittle, fairly fusible, and is used to produce other alloys,including steel. Wrought iron contains only a few tenths of a percent of carbon, is tough, malleable, less fusible, and has usually a “fibrous” structure.Carbon steel is an alloy of iron with carbon, with small amounts of Mn, S, P, and Si. Alloy steels are carbon steels with other additives such as nickel,chromium, vanadium, etc. Iron is the cheapest and most abundant, useful, and important of all metals. Natural iron contains four isotopes and isomers.Twenty one other isotopes and isomers, all radioactive, are now recognized. 1

• "...a small amount of carbon in iron greatly improves its hardness." 2
• "hemoglobin, energy metabolism" 3
• "Iron, which evidently is the main constituent of the Earth's molten metallic core, is widespread in oxidized forms in igneous rocks; it is extracted from deposits of hematite (Fe2O3), magnetite (Fe3O4), or goethite [α-FeO(OH)]. Despite the emergence of newer materials, iron and steels remain the sine qua non of the construction, transportation, energy, manufacturing, and packaging industries." 4
• "When a mixture of aluminum powder and iron(III) oxide (called thermite) is ignited, it reacts in a spectacular incandescent shower, producing molten iron. The molten iron from the reaction of thermite has been used for welding.

The process for preparing iron from its ores was discovered very early, certainly before the thirteenth century B.C. Perhaps the metal was found in the ashes of a fire built on an outcropping of iron ore, such as hematite (Fe2O3), magnetite (Fe3O4), or siderite (FeCO3). The ore would have been reduced by charcoal (carbon) at the high temperatures of the fire to yield iron.

Today, iron is produced in a blast furnace by a similar reduction. A mixture of iron ore, coke (carbon produced by heating coal), and limestone is added at the top of the furnace, and a blast of heated air enters at the bottom. Near the bottom of the furnace, the coke burns to carbon dioxide. As the carbon dioxide rises through the heated coke, it is reduced to carbon monoxide. The carbon monoxide then reduces the iron ore to metallic iron...Molten iron flows to the bottom of the blast furnace, where it is drawn off. Impurities in the iron ore react with calcium oxide from the limestone to produce a glassy material called slag. Molten slag collects in a layer floating on the molten iron and is drawn off periodically.

Steels are alloys containing over 50% iron and up to about 1.5% carbon. The iron obtained from a blast furnace (called pig iron) contains a number of impurities, including 3% to 4% carbon, that make it brittle. To produce steel, we must remove these impurities and reduce the carbon content of the iron. The basic oxygen process is a method of making steel by blowing oxygen into the molten iron to oxidize impurities and decrease the amount of carbon present. Other metals may be added to the steel to give it desired properties. Stainless steels, for example, contain 12% to 18% chromium and 8% nickel." 5

Propiedades físicas

Punto de fusion:6*  1538 °C = 1811.15 K = 2800.4 °F
Punto de ebullición:6* 2861 °C = 3134.15 K = 5181.8 °F
Punto de sublimación:6 
Triple punto:6 
Punto crítico:6 
Densidad:7  7.87 g/cm3

* - at 1 atm

Configuración electronica

Configuración electronica: [Ar] 4s2 3d6
Bloquear: d
Ocupado más alto nivel de energía: 4
Electrones de valencia: 

Números cuánticos:

n = 3
ℓ = 2
m = -2
ms = -½

Vinculación

electronegatividad (escala de Pauling):8 1.83
Electropositivity (escala de Pauling): 2.17
Afinidad electronica:9 0.151 eV
estados de oxidación: +3,2
Función del trabajo:10 4.65 eV = 7.4493E-19 J

potencial de ionización   eV 11  kJ/mol  
1 7.9024    762.5
2 16.1878    1561.9
3 30.652    2957.5
4 54.8    5287.4
5 75    7236.4
6 99.1    9561.7
7 124.98    12058.7
8 151.06    14575.1
potencial de ionización   eV 11  kJ/mol  
9 233.6    22539.0
10 262.1    25288.8
11 290.2    28000.0
12 330.8    31917.3
13 361    34831.2
14 392.2    37841.5
15 457    44093.8
16 489.256    47206.0
17 1266    122150.4
potencial de ionización   eV 11  kJ/mol  
18 1358    131027.0
19 1456    140482.6
20 1582    152639.8
21 1689    162963.7
22 1799    173577.1
23 1950    188146.4
24 2023    195189.8
25 8828    851772.3
26 9277.69    895160.8

termoquímica

Calor especifico: 0.449 J/g°C 12 = 25.074 J/mol°C = 0.107 cal/g°C = 5.993 cal/mol°C
Conductividad térmica: 80.2 (W/m)/K, 27°C 13
Calor de fusión: 13.8 kJ/mol 14 = 247.1 J/g
Calor de vaporización: 349.6 kJ/mol 15 = 6260.2 J/g
Estado de la materia Entalpía de formación (ΔHf°)16 entropía (S°)16 Energía libre de Gibbs (ΔGf°)16
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s alpha) 0 0 6.52 27.27968 0 0
(ℓ) 3.138 13.129392 8.195 34.28788 2.641 11.049944

isótopos

nucleido Masa 17 Media vida 17 spin nuclear 17 Energía de unión
45Fe 45.01458(24)# 4.9(15) ms [3.8(+20-8) ms] 3/2+# 329.83 MeV
46Fe 46.00081(38)# 9(4) ms [12(+4-3) ms] 0+ 350.94 MeV
47Fe 46.99289(28)# 21.8(7) ms 7/2-# 366.46 MeV
48Fe 47.98050(8)# 44(7) ms 0+ 385.71 MeV
49Fe 48.97361(16)# 70(3) ms (7/2-) 400.30 MeV
50Fe 49.96299(6) 155(11) ms 0+ 418.62 MeV
51Fe 50.956820(16) 305(5) ms 5/2- 432.28 MeV
52Fe 51.948114(7) 8.275(8) h 0+ 447.80 MeV
53Fe 52.9453079(19) 8.51(2) min 7/2- 458.67 MeV
54Fe 53.9396105(7) ESTABLE 0+ 472.33 MeV
55Fe 54.9382934(7) 2.737(11) a 3/2- 481.33 MeV
56Fe 55.9349375(7) ESTABLE 0+ 493.13 MeV
57Fe 56.9353940(7) ESTABLE 1/2- 500.27 MeV
58Fe 57.9332756(8) ESTABLE 0+ 510.20 MeV
59Fe 58.9348755(8) 44.495(9) d 3/2- 517.34 MeV
60Fe 59.934072(4) 1.5(3)E+6 a 0+ 525.42 MeV
61Fe 60.936745(21) 5.98(6) min 3/2-,5/2- 531.62 MeV
62Fe 61.936767(16) 68(2) s 0+ 539.70 MeV
63Fe 62.94037(18) 6.1(6) s (5/2)- 544.04 MeV
64Fe 63.9412(3) 2.0(2) s 0+ 551.18 MeV
65Fe 64.94538(26) 1.3(3) s 1/2-# 555.53 MeV
66Fe 65.94678(32) 440(40) ms 0+ 562.67 MeV
67Fe 66.95095(45) 394(9) ms 1/2-# 567.01 MeV
68Fe 67.95370(75) 187(6) ms 0+ 572.29 MeV
69Fe 68.95878(54)# 109(9) ms 1/2-# 575.70 MeV
70Fe 69.96146(64)# 94(17) ms 0+ 580.98 MeV
71Fe 70.96672(86)# 30# ms [>300 ns] 7/2+# 584.39 MeV
72Fe 71.96962(86)# 10# ms [>300 ns] 0+ 589.67 MeV
Los valores marcados con # no son puramente derivan de los datos experimentales, pero al menos en parte, de las tendencias sistemáticas. Hace girar con débiles argumentos de asignación se incluyen entre paréntesis. 17

reacciones

Abundancia

Tierra - Los compuestos de origen: oxides 34
Tierra - Agua de mar: 0.002 mg/L 35
Tierra -  Corteza:  56300 mg/kg = 5.63% 35
Tierra -  Manto:  13.3% 36
Tierra -  Núcleo:  88.6% 36
Tierra -  litosfera:  6.2% 37
Tierra -  Total:  32.07% 38
Planeta mercurio) -  Total:  64.47% 38
Venus -  Total:  31.17% 38
Universo -  Total:  0.19% 36
condritas - Total: 6.9×105 (relative to 106 atoms of Si) 39
Cuerpo humano - Total: 0.006% 40

Compuestos

Información de seguridad

NFPA 704 Ratings:
Health: 0 - Poses no health hazard, no precautions necessary.
Flammability: 1 - Must be heated before ignition can occur. Flash point over 93°C (200°F).
Reactivity: 1 - Normally stable, but can become unstable at elevated temperatures and pressures.

Ficha de datos de seguridad de materiales - ACI Alloys, Inc.

Para más información

Enlaces externos:

Fuentes

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